Are injuries up?
That question has been asked repeatedly over the first two months of the 2013-14 NBA season, and especially loudly on Friday after All-Stars Al Horford and Russell Westbrook were sidelined for extended periods. Since keeping track of injuries for 400-plus players and 30 teams is nearly impossible, this is an area where turning to the data is especially useful. For the last five seasons, I've been tracking NBA injuries to answer questions like this. Let's take a look at what the numbers say.
Injuries up? Probably, but not that much
My injury database, originally compiled for Basketball Prospectus with the help of researchers Dirk van Duym and Joe Dombrowski, dates back to the 2009-10 season using publicly available data on games lost to injury (including illness, but not games missed due to suspension).
Season Injuries/game
2009-10 3.2
2010-11 3.8
2011-12 3.8
2012-13 3.2
2013-14 3.7
Through Saturday, there have been an average of 3.7 games lost to injury for each NBA game. That is, the typical game will have two players on each team sidelined. As the table at the right indicates, that's up from last season (3.2 injuries per game), but not out of the ordinary.
The ratio of games missed was slightly higher in both 2011-12, the abbreviated post-lockout season, and 2010-11. (Using the slightly different measure of "significant" injuries, an NBA spokesperson told Bleacher Report that this season's numbers are typical and 2010-11 was a particularly bad season.)
Case closed? Well, not quite. It's difficult to compare injury data from the first two months of the season to a full schedule because maladies tend to accumulate over the course of the season. More players will be injured, while the ones who have already suffered season-ending injuries won't come back.
A better way to look at the data midseason, then, is to compare the number of new injuries suffered by date. (Technically, by first game missed, so the first day of the season includes players rehabbing from prior injuries.) Graphing injuries by date gives some ammunition to observers who believe injuries are up:
Injuries Chart
ESPN Stats and Information
There were many more injuries each day after the lockout, in part because there were simply more games per day. Whether the compact schedule actually caused more injuries is more difficult to say. In some cases, the apparent rise in injuries may have been due to the fact that players missed games due to the schedule when otherwise they would have only sat out a practice day.
Anyway, injuries occurred at a similar rate during the other three seasons in the database, and were remarkably consistent over the course of the schedule. So far, the pace has been faster this season, which is reinforced by zooming in on just the first two months of the previous graph.
Injuries Chart
ESPN Stats and Information
At the same time, were the current pace to continue, for the full season we'd only see about 45 more total injuries than we saw in 2012-13. And past campaigns have had periods with high injury frequency before returning to the typical rate. For example, through November 2009, injuries appeared to be up, but that trend proved nothing more than noise.
Sidelined stars
One explanation for why it seems like injuries are on the rise is the quality of players who have been knocked out of lineups. Even before Horford and Westbrook, All-Stars like Kobe Bryant, Marc Gasol, Brook Lopez, Steve Nash, Rajon Rondo and Derrick Rose had suffered serious injuries that forced them to miss extended periods, if not the entire season.
Still, it would be hard for this season's list of injured All-Stars to compare with last season's group -- which, of course, also included Bryant, Nash, Rondo, Rose and Westbrook as well as Kevin Love and Andrew Bynum. The 15 members of the 2011-12 All-NBA teams combined to miss 297 games due to injury last season, an abnormally large number. By contrast, last season's All-NBAers (including Bryant, Gasol and Westbrook) are on pace to miss fewer than 200 games total this season.
TYPICAL INJURY
Season MPG Win%
2009-10 21.3 .484
2010-11 20.1 .468
2011-12 23.8 .477
2012-13 23.2 .506
2013-14 21.0 .482
Another way to look at the quality of players lost to injury is to find the average minutes per game and per-minute win percentage rating of this group, weighted by number of games missed. Last season was the only time in the last five years that the typical player rated better than league average (.500), and the typical minutes per game played by injured players is also down this season (see chart at right). That agrees with what Rotowire's Jeff Stotts found, using average salary as a gauge of player quality.
Tricking ourselves into seeing rising injury rates
I don't have data from before the 2009-10 season, and a long-term study of injury rates would be difficult because of the way teams were forced to invent injuries for players they wanted to keep on the injured list before it was replaced with the current inactive list in 2005-06. So I can't really disprove the notion that players are getting injured more frequently.
Still, I suspect this widespread sentiment is the result of a trick our brains play on us. The availability heuristic is an example of cognitive bias that makes events we can recall seem more meaningful than those that are hidden deep in our memory. Since recent injuries are inevitably easier to remember -- can you recall which stars were sidelined this time a decade ago? -- our memory tricks us into thinking injuries are increasing.
This issue is exacerbated by the fact that clean health is even more difficult to notice. When a player enjoys good health, it's not a story. It's the expected outcome, though we know that every player has a chance of suffering an injury. By contrast, when a star goes down, it's front-page news here on ESPN.com and elsewhere.
Recognizing this bias is the first step to overcoming it. The next is to make use of objective data, and so far they don't really indicate that injuries are on the rise.
첫댓글 올해가 유독 부상이 많네 어쩌네 하지만 그런 글은 매 시즌마다 올라오죠. 단지 이름있는 선수들의 부상 때문에 임팩트가 있어보이는 겁니다.
부상이 유독 많은게 아니라면 매년 부상이 지금처럼 엄청나게 일어난다는 얘기지요.
리그는 이 고질적인 부상 문제들을 어떻게 해결할 지 고민이라도 해봤으면 좋겠습니다.
매번 감사합니다
유리몸이여서 더 집중해서 봤네요 ㅠ
좋은 정보 감사드립니다~!! ^^