Basketball in the Olympics

Note: I took a summer break from this, but I'll be back with an article or two a week including more statistical analysis.

Introduction

David Stern suggested that the Olympics and the World Championships should be limit NBA players to those who are 23 years-old or younger. One of the issues is the risk involved in letting multi-million dollar assets compete during the summer with the possibility of a long-term injury suffered during the summer. Mark Cuban is one of the most vocal opponents of NBA stars playing in competitions, and from his perspective it's about protecting a valuable commodity rather than letting human players represent their country in a global celebration of both their sport and all sports. This comes up every summer there's a tournament, and people assume that it leads to a negative effect on NBA players from either getting injured that summer (rare) or suffering one in the regular season due to "stress" from already playing too much in the summer. Of course, no one has actually looked through the numbers to see if this is actually true. In this article I'll be looking at whether or not players do indeed suffer a negative effect in terms of games missed or injuries accrued from playing in either the Olympics or the World Championship in every tournament where NBA players are used since 1992, the original Dream Team.

Games Missed Before a Tournament Versus After a Tournament

The most obvious way to answer this question is to simply look at how many games players log in the regular season before the summer tournament and after. Focusing on just those adjacent seasons minimizes the effects of aging players missing more games or any other similar systematic error. Using every team from 1992 and on (nine total because 1998 occurred during the lockout and 2012 obviously doesn't have an "after" season for comparison), there are 2056 player seasons with which to work. This is limited, however, to American players to keep the data as homogeneous as possible. The lockout seasons are adjusted for an 82 game equivalent. The span is from Dominique Wilkins to Stephen Curry. The good thing with looking at star players, which are the bulk of those selected to the teams, is that they will not miss games due to a coach's decision (i.e. not being good enough to play), improving the data set by maximizing the number of legitimate games missed solely because of an injury. Obviously with real data nothing is ever perfect, and effects like tanking pollute the results, but it's definitely usable.

Table 1: Comparison of games played before and after summer competition

Regular season before	Regular season after
75.8	71.0

Averaging nearly 76 games for a regular season is actually quite impressive, but there's a noticeable drop-off following a summer competition -- 4.8 games, specifically. Note that restricting this to seasons before and after the summer drops the sample size down to 204 seasons. Now if this was Mythbusters or an ESPN article we'd leave it at that and move on, thinking players average less games after the Olympics, but it's not much more work to go a little further and definitively answer the question.

Using a student T-test with two tails (more conservative) on the before and after seasons assuming unequal variances, there's significant evidence that NBA summer Olympic and World Championship participants play less games the following regular season. Specifically, there's a 0.31% chance the null hypothesis was correct -- that regular seasons after a summer competition are the same in terms of games played. However, it's a small difference and one year of aging does make a considerable impact on how many games you play a year.

Regression of Games Missed, a Summer Competition, and Age

A simple regression was conducted to predict the number of games played given age and whether or not the player was in an Olympic or World Championship tournament the summer before. This includes every season from every professional in the competitions, even Larry Bird who played the games after his last season in the NBA. The summer competition is a dummy variable, which for the uninitiated is the slanderous name for a variable that is either 0 or 1 (i.e. the mere  presence of a summer competition.) Below is a graph with the regression results.

	Coefficient	Standard error	p-value
Intercept	89.9	2.16	2.81E-275
Age	-0.713	0.0765	2.74E-20
Summer competition	4.14	1.65	0.0124
R^2	0.04553
Adj. R^2	0.04460
Standard error	16.3
Degrees of freedom	2053
F-statistic for inclusion of summer variable	0.0124

The F-statistic is showing the significance of the presented model with one that doesn't include the summer competition variable. In other words, there's only a 1.24% chance that a summer tournament significantly changes the number of games a player participates in the following season, and by (mostly) coincidence it's the same p-value for the summer competition coefficient (note: to reiterate they are different statistics because one is a statistic between regression models and another looks at the standard error of a single coefficient in one model.) The level of significance is traditionally 5% or lower, while what's known as a "very high" level of significance is 1% or lower. To put that in other words, there is no strong evidence here that guys miss more games in the summer, but it is evidence.

One alternative explanation stems from the fact that the data are not randomly selected. If a player is injured, then that player is less likely to be used in the summer games. However, what that means is the data population is biased: the pool used is healthier than normal the season before as otherwise they wouldn't play. There are few ways to remedy the selection bias of the games. Ideally, you want random selection, but coaches opt for certain players instead, or the players take themselves out of the games. Andrew Bynum is a good example: a player with an extensive history of injury problems is less likely to attend the Olympics or FIBA play than otherwise, which distorts the data set in how players are selected. Also, using players from other countries who played in the Olympics invites other biases, and then you have to deal with digging through other leagues and trying to apply the same set of statistical assumptions to everyone.

Conclusion

In the real world, "proving" whether or not certain theories are true is a complicated process loaded with problematic assumptions and funky data. It is bad practice to point to numbers and proclaim, "This is true because this number is big, and this other number is small." Looking at the weak statistical evidence and how players are more likely to be healthy the season before the games than after because healthy players are more likely to be chosen, the hypothesis that summer games from the Olympics and the FIBA World Championship causes NBA players to miss significant time has not been substantiated from this method. A longer-term and more exhaustive study is needed to answer the question, but unfortunately there's always the problem that Olympic/Championship players are distinct from everyone else, making the analysis more elusive. One interesting fact, however, was that one year of aging subtracts 0.7 games played, which can be used as a rough estimate when needed.

But research never ends. Throwing together the most talented young American players on the same team and having them practice and compete with each other may have other results. In an upcoming small study I'll try to figure out if the summer games help the development of NBA players.

2012 Olympics: Extreme Team's Chances

The final score of the USA-Spain exhibition game belies the weakness Team USA showed. Spain blitzed to an early lead and embarrassed the favorites with crisp passing, Pau's post game, and a sloppy US squad. Of course, the lead after the first quarter was only two points and by halftime the US had already usurped them; by the end of the game it was a blowout. But there's a legitimate thread of reasoning for concern now that's surfaced in the lauded '12 Extreme(-ly small but athletic) Team. 

The most important point about this game is that Spain wasn't looking to win. It was an exhibition game whose result had absolutely no direct bearing on the Olympic tournament. A win would be just an abstraction. Maybe it would help the Spain's confidence during the following games, but that's the only type of loose benefit the team could extract. Since there is nothing objective to gain from winning, all important strategies against Team USA would be pointless to employ. Thus, any special play will be shelved until they meet again and a weapon like a zone defense or pick and roll should not be used frequently so the Americans can't learn to defend or play against it. Also, they don't need to force a player with an injury (Marc Gasol) onto the court or play their most important pieces large minutes. An insanely deep team like USA doesn't need to worry about that, but other teams usually have a few stars they hope could play the entire game. (USA arguably has LeBron in that position, showing how amazing he is.)

Team USA, by contrast, cannot even lose in an exhibition game because of the enormous expectations placed on them. So it was no surprise to see LeBron and Durant to play 28 and 29 minutes, respectively, while Gasol and Calderon only played 24 and 27 minutes. The amazing bench from Team USA couldn't even close the gap for reducing minutes.

The Extreme Team's glaring weakness, centers and subsequently frontcourt defense against big players, is a terrible match-up for Spain (and Brazil). Both Gasol brothers are legitimate 7-footers and USA's only counter is Tyson Chandler. Against only one Gasol Chandler fouled out in eight minutes; that does not bode well for the future. With Chandler out of the game here are their options: Kevin Love, who was destroyed defensively and stands 6' 8" with no vertical leaping skills and fairly short arms; Anthony Davis, who has not even played a single minute in the NBA; or a small forward like their two leading scorers Durant and James.With both Gasol brothers one of those other options will need to cover (most likely) Pau, and in the doomsday scenario, which is not entirely unlikely, Team USA will need to defend both without their only center. Pau scored 19 points in a little under 24 minutes while drawing ten fouls. It's frightening to consider what they could do when they're both playing well.

The primary strength of Team USA is their combination of speed and athleticism, which allows them to smother opponents in the backcourt and start transition plays that typically end in a dunk. Spain, however, has Jose Calderon, a player who's led the NBA in assist-to-turnover ratio three times over the past five seasons including an incredible 5.38 in 07-2008. Appropriately, Chris Paul is his nearest peer and has led the league the only two times Calderon hasn't. With a steady hand at the helm, their full-court defense and ball pressure is rendered ineffective, stunting the Retread Team's offense -- no easy dunks in the open court means there are more possessions with an all-star team that's still uncomfortable playing a half-court offense. Against Tunisia this will work, but not against a good backcourt.

Another concern is luck. In a one-and-done tournament, something as chaotic as the result of a three point shot has a huge effect on the outcome. The Extreme Team was 13/23 from three point land and Spain 5/19. It could have easily gone the other way, and with Marc Gasol playing suddenly Spain looks venomous. Carmelo Anthony isn't a marksmen from outside despite his superstar label; don't expect him to hit 5/8 of his shots from there with regularity. If we're speaking of luck, some will point out that Rubio isn't playing, but Team USA has an all-star team from guys who are also out with injuries -- Dwight Howard (they really need him too), Derrick Rose, Chris Bosh, Blake Griffin, etc.

The Miami Heat and Team USA have a lot in common defensively. Team USA relies on switches and quick coverage overwhelming teams with athleticism. They also like to field a team with little variation in height; this allows for more switches on pick and rolls and a defense that is basically an amorphous, interchangeable system of parts. Joel Anthony is Miami's nominal center, but even he's a bit short and the team likes to play without a traditional center. Versus Oklahoma City this was fine because Perkins wasn't going to score 30 in the post, but against the Gasol Brothers (plus Ibaka, strangely enough, who seems to be liberated offensively) and Brazil's line of Nene-Splitter-Varejao. Another weakness of this approach is that Miami will often leave shooters open in the corners. While it's not entirely accurate to assume the same will happen to Team USA, constant switching and a swarming, pressuring defense can be defeated by crisp passing. If you swing the ball around enough even the fastest players in the world can cover every square foot of the court. Calderon is also adept at finding big men inside, and if Carmelo Anthony or Kevin Love are part of the frontcourt there will be little resistance at the rim.

I still believe Team USA is the favorite to win the gold medal in London. One disadvantage that won't be (as) present is the home-court advantage for Spain since they were playing in their home country, and England is fond of the Americans as almost any European country. The FIBA officials will still be horrendous, but probably not as bad. (There were some calls during the game that were laughably bad; please watch FIBA basketball to gain back your respect of NBA officiating.) The Retread team is still a vulnerable team, however, especially in the frontcourt. Their best hope is that Anthony Davis gets more playing time and establishes himself as a part of the rotation because they'll need his shot-blocking and length. One Tyson Chandler is better than none, but the problem with having one of a kind is that teams can focus on getting him in foul trouble where only five gets you thrown out in the Olympics. The difficulty level has risen to "expert", and one wrong move will derail this cast of talent. It will take more than brute strength to repeat with gold; this time they will need guile, will, cunning, and a little bit of luck.

Interesting finds from the cumulative exhibition game stats:

-Tyson Chandler has more fouls than points.

-Anthony Davis has more points than Kevin Love.

-Their leading rebounder is Durant, although Love isn't too far from the lead in like 40% of the minutes.

-Leading shot-blocker is Davis even though he's only played 27 minutes.

-Westbrook has the best free-throw percentage on the team.

Stay Humble, Stay Hungry: 2012 Olympics

There is a lot of enthusiasm for this year's Olympic squad and even though Dwight Howard and others are injured they are highly favored. Check out some quotes about the team:



-"Our speed," the reigning NBA MVP said Saturday night after the final roster was announced. "Our speed is one of the best, and also how dynamic some of the lineups can be, [guys] being able to play a lot of positions."


-With the group of core players announced today, we have a strong foundation to the team as the roster contains a great blend of veterans and youth along with athleticism, talent and the all-important factor of international basketball experience."


-"We can play fast; we can play big. We can put a team of shooters on the floor, or go with a slash-and-penetrate lineup. I think defensively, we'll be able to throw different looks out there as well. From my standpoint, it will be fun having so many different ways to play the game of basketball. 


-Therein lies Team USA's biggest strength as it gears up for London. The speed and athleticism that Krzyzewski has to choose from is ridiculous.


-"We've added athleticism, defense, three-point shooting, ball-handling. I love the versatility of our lineup, and I think this summer is going to be a lot of fun."


-The Americans will look to run whenever they can and they know that if they can come together as a group and play solid defense throughout they should be walking away with yet another gold medal in London.


-"These players represent some of the top talent in the NBA and the team possesses tremendous versatility and athleticism. I'm certain that these players will represent the United States in a manner that will make all Americans proud." 


What's the problem then? Well, those quotes are mixed with ones from the 2002 debacle in Indianapolis where the Americans left with the same record as Puerto Rico and a seventh place finish on their home soil. Only the first, fourth, and sixth quotes refer to the London Games, while the others can be found here and here.When the rest of the world was catching up to the Americans in basketball in the early part of the 00's decade, the US was assuming its talent and athleticism would trump anything another country could produce, even if they had superior chemistry from playing together and being constructed as an actual team. They got through the first preliminary round loss-free, but fell to a superbly talented Argentina team and stained their legacy in the second preliminary round. Sure, they didn't win the world championship in '98, but it was a lockout and college players were used. During the first knock-out stage, however, they lost to Yugoslavia by three points, and subsequently wound up in sixth place overall after losing to Spain.

Very few people were paying attention to the FIBA world championship, so the disgrace of the team spread through the news cycle like an oil spill in a foreign land. People retroactively explained that the team was poorly constructed and stood little chance against teams that often employed NBA-caliber talent in cohesive units who had been playing for years. Like so many things, it took a catastrophe for people to notice, and swift changes were made ... well, they didn't win again until 2008 with the Redeem Team, but the mid 00's regularly featured lots of talk about how the mighty US had fallen in basketball and how to fix it.

What people finally realized is that you can't throw a bunch of big names on a team and expect domination. You need to field a real team without holes and allow them enough time to gel. For instance, here's a list of needs to fulfill while you field a roster (and obviously one guy can take up more than one category):
-True point guards who can pass with at least one back-up in case there are injuries or issues with the starting one.
-A tough, versatile perimeter stopper with a back-up to shut down the other team's star as international teams usually have one very good player.
-Outside shooters to bust zones and take advantage of the shorter line. Need at least three very good outside shooters in case one is cold from the field, and at least one needs to be one of the best outside shooters in the world.
-Shot creators who can carry the offense (we'll never be low on that.)
-Strong low-post defenders and preferably two. USA has been carved up by post players in the past, like with Baby Shaq on Greece
-Two true centers to protect the rim (separate category because they're different skills)
-Rebounders to control the boards including two elite guys with surrounding help.

The problem last decade was the drought of good, "true" point guards. Kidd was slated to be on the 2002 team but was forced out by an injury and the next best guy was Andre Miller, whose lack of a jump shot made him a liability in the international game. Kidd couldn't shoot either, but his passing and defensive skills were great enough to overcome that while Miller has yet to visit an all-star game. Looking at this year's roster we're doing pretty good with a notable exception in the frontcount.

Chris Paul
Deron Williams
Russell Westbrook
Kobe Bryant
James Harden
Andre Iguodala
LeBron James
Kevin Durant
Carmelo Anthony
Kevin Love
Blake Griffin
Tyson Chandler

True points guards: Chris Paul and Deron Williams
Perimeter stopper: Iguodala and James (and Bryant since he's had that role before)
Zone busters: Durant and Harden ... and Paul and Williams and Love and Bryant (though he hasn't been shooting well from the NBA three last few years)
Shot creators: every perimeter player except Iguodala
Low-post defenders: Tyson Chandler
Rim protector: Tyson Chandler
Rebounders: Tyson Chandler, Love and Griffin (though you'd also have to mention guys like James too)

Obviously, Howard's injury completely changed the team, but Team USA should have had a better back-up plan than Tyson Chandler and Griffin or Love at center. There were options, and even though Anthony Davis sprained his ankle so they couldn't see him in person you have to be pretty sure he's a better rim protector than Griffin. There was also Cousins who could have provided a big body if need be; coach K commented on his maturity but this is the experience he needs to mature as a person and the coach should be used to guys like that seeing as how he coaches college players (well, it's Duke, but Austin Rivers shows you can be rich and still a pain.) He could have been mentored by Tyson Chandler and other vets on how to be professional. It's too bad Hibbert played for Jamaica because they could have used him as a back-up true center, but he did ask for a release.

Bynum is the only other American center besides Howard and faintly Hibbert with the star label, but with his injury history people keep him far away from the game. There are also a few veterans who could help but are far too old to convince like Garnett or Duncan. It's better to just target guys with a mix of talent who can help you cover all the defensive aspects you need while half will ideally space the floor like Love or Aldridge. Taj Gibson, for example, is a member on the select team and would be a fine addition as a 12th man for his defense.

There are a few players who USA doesn't really need. Kobe Bryant isn't what he once was and not even that great of an outside shooter. He's basically there as the wise old vet like Kidd was, and that's not really the worst pick. Carmelo Anthony duplicates a lot of what they already have, but he usually plays very well in the international games and he wants to be there so it's hard to keep him off. Blake Griffin is probably the easiest to let go because he doesn't have an outside shot and can't defend. Then again, he exists solely to throw down an all-time dunk against a player who has no hope of defending him like Carter over Weis in 2000. However, picking a player just because he's an exciting dunker is precisely the strategy that led to the US's downfall, and in fact in 2000 the team was one shot away from losing. Harden is another favorite to jettison, but his outside shooting is valuable and his beard can merge nations. Actually, I think the easiest guy to let go is Westbrook. They already have two great point guards, and if they're really so upset about losing a third then why don't they care they only have one center who has a history of injuries? With James and Iguodala and others someone else can also steer the ship on offense.

While the US has won the past two world championships from the 2008 Olympics and the 2010 world championships, it is best to remain cautious and not lose sight of how easy it is to lose in a single game elimination tournament. One bad mismatch and a player no American has heard of will play incredibly and Team USA could lose. To avoid that the team needs to be constructed with few holes and utilize the characteristics of the international game. There is a lot of outside shooting because of the shorter line, but an inside player can still wreck havoc like Sofoklis Schortsanitis in 2004. I think this is a good team but there's an obvious hole in the middle and anyone saying it doesn't matter because of the team's athleticism should check history first. With that said, here's my ideal team with no injuries:

Chris Paul
Deron Williams
Kyle Lowry
Stephen Curry
Andre Iguodala
LeBron James
Kevin Durant
Kevin Love
Chris Bosh
Kevin Garnett
Dwight Howard
Tyson Chandler

(My favorite part is the number of amazing line-ups possible like the defensive juggernaut of Kyle Lowry-Iguodala-James-Garnett-Howard.)

And here's the team constructed in reality:

Chris Paul
Deron Williams
Kyle Lowry
Tony Allen
Andre Iguodala
James Harden
LeBron James
Kevin Durant
Kevin Love
Taj Gibson
Tyson Chandler
DeMarcus Cousins

I'd save Paul for crucial minutes and give more to Williams and Lowry. Allen wouldn't be used all too often and more like a break-in-case-of-fire type of guy. Iggy and Harden would log pretty big minutes because Iggy is a fantastic big defender who pretty's good on offense and Harden is amazingly efficient. With Allen and Iguodala along with the high scorers on the team James wouldn't carry a big load until Spain or another big thread. Durant would likely be the top scorer, and Love would rack up a lot of time unless there was a bad defensive match-up. Gibson would appear mostly in blowout games and when he's needed for his defense. Same is true for Cousins except only when his big body is needed against the largest opponents. Chandler would be rested as much as possible with the US playing small a lot. He would play brief minutes against a team like Angola, for example.

Offensive lineup:
Chris Paul-Harden-Durant-James-Love

Defensive lineup:
Lowry-Tony Allen-James-Gibson-Chandler

Starting lineup:
Chris Paul-Iguodala-James-Love-Chandler