Writers of Pro Football Prospectus 2008

28 Aug 2010

Which Teams Over- or Under-Report Injuries?

Adjusted Games Lost (AGL), our injury metric at Football Outsiders, makes sense of the injury report by incorporating the historical likelihood of a player with a given status and role on the team missing a game.

As an example, from 2007 through 2009, a starter on a team who was listed as "Doubtful" on the injury report in a given week only played 3.7 percent of the time. As a result, each time a starter appears on the injury report as "Doubtful," AGL values him as having missed .963 games, regardless of whether he actually plays or not.

It gets a little more complex than that for the actual calculation of AGL -- we're incorporating a rolling baseline for the year in question (owing to holes in data for the 1996-1999 campaigns) and also adjusting for the position in question.

This does an effective job of encapsulating the impact of injuries on teams, but one of the factors it doesn't consider is how individual teams may game the injury report. It's easy to imagine one team listing every player with a minor nick as "Probable," while another team simply leaves those players off of the report. The difference in AGL wouldn't be very dramatic, even over the course of one season, but it could add up over the course of several seasons.

To figure out which teams have deviated furthest from their injury report expectations, I calculated an "expected" number of games missed using AGL. As an example, from 2007 through 2009, the mix of players the Cardinals listed on the injury report would have yielded an expected 249 games missed by their players over that three-year stretch. The Cardinals actually had their players miss 239 games over that timeframe, so Arizona has played the injured guys on their roster about four percent more frequently than league average. (Since 239 is less than 249, in the subsequent chart, this is reported as -4.0 percent.)

From 2007-2009, there was one team that manipulated the injury report far more than any other:

Table 1: Expected Games Lost vs. Actual Games Lost
Team Exp Act Diff Pct
NYJ 211.4 183 -28.4 -13.4%
ATL 365.4 336 -29.4 -8.1%
CLE 425.6 397 -28.6 -6.7%
SD 247.6 231 -16.6 -6.7%
TB 401.6 382 -19.6 -4.9%
ARI 249.0 239 -10.0 -4.0%
PHI 276.5 266 -10.5 -3.8%
NE 456.6 444 -12.6 -2.8%
CAR 333.9 325 -8.9 -2.7%
MIA 263.5 257 -6.5 -2.5%
BAL 505.2 497 -8.2 -1.6%
DAL 259.7 257 -2.7 -1.0%
MIN 216.9 215 -1.9 -0.9%
BUF 474.3 471 -3.3 -0.7%
DET 532.2 531 -1.2 -0.2%
WAS 281.5 281 -0.5 -0.2%
Table 1: Expected Games Lost vs. Actual Games Lost
Team Exp Act Diff Pct
CHI 305.3 307 1.7 0.6%
OAK 338.4 341 2.6 0.8%
HOU 354.5 360 5.5 1.6%
NYG 373.8 381 7.2 1.9%
STL 446.7 456 9.3 2.1%
PIT 275.9 282 6.1 2.2%
NO 460.6 472 11.4 2.5%
CIN 500.4 514 13.6 2.7%
GB 461.8 475 13.2 2.9%
SF 283.8 293 9.2 3.3%
DEN 359.2 374 14.8 4.1%
JAC 407.7 425 17.3 4.2%
TEN 247.9 259 11.1 4.5%
SEA 319.4 340 20.6 6.5%
IND 388.4 415 26.6 6.9%
KC 271.3 290 18.7 6.9%

The issue of the Jets manipulating the injury report is nothing new. The linked article discusses Eric Mangini's affinity for playing games, though, and he's no longer the Jets coach. So did the Jets continue to mess around after Rex Ryan took over?

The answer is no. Under Mangini in 2007 and 2008, the Jets "reported" 181.1 games missed. Their players actually missed 153 games, for a difference of 28.1 games (15.5 percent). Last year, with Ryan running the show, the Jets reported 30.3 AGL worth of injuries and their players missed 30 games. Meanwhile, with Mangini in Cleveland, he reported 153.1 AGL worth of injuries and his players actually missed 141 games, a difference of 12.1 games (7.9 percent).

I was surprised to see teams like Kansas City and Indianapolis on the other side of the coin. Tennessee, which finished fourth, wasn't as surprising: At points during Jeff Fisher's tenure, the Titans have stopped listing players as "Probable" altogether. That's no longer the case, but it's a sign of how Fisher views the injury report. The real difference in how Fisher uses the report nowadays is when players are listed as "Questionable." The difference in expected games missed by "Probable" Titans players is pretty tiny (eight actual games missed vs. 6.4 expected games missed in 91 instances), but Titans players listed as "Questionable" have missed 69 games versus 59.2 expected misses (in 133 instances).

I suspect our readers in Nevada and outside of America may also find this data particularly interesting.

Posted by: Bill Barnwell on 28 Aug 2010

14 comments, Last at 30 Aug 2010, 9:21pm by mm

Comments

1
by Nate Dunlevy (not verified) :: Sat, 08/28/2010 - 5:42pm

Why were you surprised about the Colts? They have had the rep for hiding injuries and under reporting who was really hurt and how bad for years.

2
by Temo :: Sat, 08/28/2010 - 5:46pm

I'm not sure, but I think I'm still holding Anthony Gonzalez on my fantasy team, waiting for that promised late-season return. I swear guys, next week is the week!

11
by Bobman :: Sun, 08/29/2010 - 8:38pm

Nate: Also known fer being injured a lot!

Marvin Harrison, 2007: "We see lots of progress and hope to see him back in the lineup any day now," as the surgeon sharpens his bone saw for the amputation.....

Temo, sigh, yes, see the more painful example above. I'm expecting Harrison to round into shape and return to the lineuup any day now..... I think Bob Sanders was part of that merry-go-round a bit too. Colts faithful (at least one of us) just assume the worst/most conservative gameday lineup regarding injuries, and if a player in question actually gets on the field, it's gravy. Or icing. Or icing on the gravy. mmmmm, icing on the gravy, gotta go--dinner time.

12
by jp6v (not verified) :: Sun, 08/29/2010 - 8:59pm

Except that's not what this table says.

3
by Iain (not verified) :: Sat, 08/28/2010 - 5:53pm

Ironic that Jets under Mangini drastically overreported injuries and ended up paying fines for *underreporting* Favre's 2008 issues.

4
by DEW (not verified) :: Sat, 08/28/2010 - 6:18pm

Hey, the Mangenius is an equal-opportunity liar! (Personally, after all the talk about Belichek, I'm amazed to see NE in the middle of the pack; maybe Mangini took all the injury-report lying with him when he left town?)

5
by Shattenjager :: Sat, 08/28/2010 - 7:17pm

Or Belichick manipulates the report in both directions.

9
by TimTheEnchanter (not verified) :: Sun, 08/29/2010 - 9:47am

Why do I have a feeling Ernie Adams was already tracking this sort of thing and making sure they were staying balanced?

10
by piratefreedom (not verified) :: Sun, 08/29/2010 - 12:08pm

because you've heard of Ernie Adams

7
by Theo :: Sat, 08/28/2010 - 7:54pm

"I suspect our readers in Nevada and outside of America may also find this data particularly interesting." [citation needed]

13
by Neoplatonist Bolthead (not verified) :: Mon, 08/30/2010 - 8:40am

You don't need to cite a source for your suspicions.

14
by mm (not verified) :: Mon, 08/30/2010 - 9:21pm

Gambling on sports is illegal in most states; Nevada is the big exception.

6
by Rob R (not verified) :: Sat, 08/28/2010 - 7:50pm

Perhaps this data would be more useful if it was broken down by coach and not team.

8
by Ken Pierce (not verified) :: Sun, 08/29/2010 - 12:12am

Rob R -- that's EXACTLY what I was thinking. Seems to me that it's likely to be, absolutely, a function of the coach's personality, not the owner's or the "local culture" or something.