Are Teams Faking Injuries? Part I

Guest Column by Jared Cohen

Conservatively, I would estimate there were about 500,000 words dedicated to NFL gamesmanship over the few months. But in all the talk about deflated balls and illegal substitutions during the 2014 playoffs, one area has remained relatively unexamined.

With an increase in fast-tempo offenses, are defenses faking injuries in an attempt to slow them down?

As a Philadelphia fan, I'm predisposed to assume there are massive conspiracies against the Eagles. So since the Eagles started running Chip Kelly's offense, my eyebrow has gone up every time an opposing defender needed an injury timeout.

The Eagles' high tempo is a part of their strategy, and one that opposing teams would love to minimize, particularly if they aren't well prepared for it. Faking an injury can mitigate a high-tempo offense, given there's no cost to the injured team outside of a timeout in the last two minutes of a half and the requirement that the injured player must sit out the next play.

This might become an even more important question after the new rule passed by NFL owners today, which will allow an athletic trainer spotter in the press box to call a timeout to pull a potential injured player out of the game. Calling injury timeouts will no longer be limited to the officials on the field, which means we are likely to see more of them.

Could teams really be faking injuries? It's an idea that's hard to critically evaluate, but using play-by-play records, we can start to see if any suspicious patterns emerge.

Data Collection and Methodology

I examined play-by-play data from all the 2014 regular-season games, and identified all the in-game injuries noted in the play descriptions. In case you haven’t read play-by-play before, each play has its own line and explanation, and any play that resulted in an injury timeout is noted. Below is an example:

2-10-DET 40 (14:05) (Shotgun) 10-E.Manning pass incomplete deep middle to 80-V.Cruz (27-G.Quin). DET-27-G.Quin was injured during the play.

If an injury was noted as a stoppage, I marked if it was suffered by the offense, defense, or special teams. There were approximately 700 total observations. (Today's article only discusses these 2014 plays; a second article later this week will discuss play-by-play data going back to 2010.)

After gathering the data, one additional adjustment required is for play frequency. The more snaps a player gets, the more likely he is to sustain an injury. Therefore, any team that runs more plays is probably going to see a higher absolute number of injuries. To account for this, I also looked up the total number of plays for each team's offense and defense during the course of the year, to understand the rate of injury rather than just total numbers.

Output

There were 692 injuries in the play-by-play data, 66 of which were special-teams plays and so were excluded (faking these wouldn't slow down an opposing offense). Looking at the rate of defensive injuries against (adjusted for number of plays), we can see which teams are seeing the highest rate of injury among their opponents -- and are potential victims of fake injuries.

When we look at it on a rate basis (number of injuries divided by number of total offensive plays), the Eagles are second in the league and roughly 50 percent above the league average.

But before we get any further down the faking rabbit hole, what if there's a simpler explanation that doesn't involve fake injuries? There's another obvious possibility to explain why the Eagles are so high in defensive injuries against. What about the idea that as you run more plays, players get more physically exhausted, and therefore are naturally more susceptible to injury?

To test this, I took a simple look at whether injury frequency varies by quarter. If teams get physically tired during the course of the game and that leads to more fatigue and more injury, there should be more injuries as the game goes on.

In absolute terms, the number of injures does rise dramatically as the game goes on. Injury stoppages in the fourth quarter occur at double the rate they do in the first quarter. Part of that can be explained by the fact that the clock stops more frequently in the fourth quarter than it does earlier in the game (and thus there are more plays), but that wouldn't explain a two-times difference.

What you've also likely noticed is that the increase is much more pronounced on the defensive side of the ball than on offense or special teams. We'll come back to that later.

For the time being, let's move on to looking for evidence of fake injuries. This time I looked for relationships between injury frequency and number of plays in specific situations.

As a general framework, I split the types of injury stoppages into four buckets:

1. While on offense, your own team suffers an injury (Own-Offense)
2. While on defense, your own team suffers an injury (Own-Defense)
3. While on defense, your opponent suffers an injury (Opponent-Offense)
4. While on offense, your opponent suffers an injury (Opponent-Defense)

We saw that overall injuries increase as the game goes on, but it seems much more prevalent on the defense, which is the side that would be interested in faking injuries. So can we look a bit deeper to see if play frequency increases injury risk across each type of injury stoppage? The idea that running more plays increases the rate of injury should not be exclusive to offense or defense, although it appears that way at first glance; it's hard for me to believe that defensive players are in any worse shape or take any harder hits than offensive players.

To take a look at the issue, I ran some basic correlations across each of those four injury types, looking at the number of plays run and the rate of injury. Just to clarify, I summarized the four below:

1. The offense runs more plays and gets injured more often (this would be a good offense)
2. The defense runs more plays and gets injured more often (this would be a bad defense)
3. The defense runs more plays and your opponent's offense gets injured more often
4. The offense runs more plays and your opponent's defense gets injured more often

Again, if the rate of injury increases with more plays, we should see relationships in each of these situations. So what do we see?

1. On the offensive side of the ball, there's actually a relatively weak negative correlation between running lots of offensive plays and suffering offensive injuries. If you want to believe in things like Chip Kelly's Sport Science program, you would expect a negative relationship as teams that employ high-tempo offenses should be more adequately prepared to stay healthy in those schemes. While a very slight negative relationship exists, it doesn't look to be that large, if it even exists at all.

2. Earlier we saw defenses suffering more injuries as the game goes on ... and yet, when we look at number of defensive plays per game and the rate of defensive injury, there really doesn't seem to be any relationship. Teams with defenses that are on the field a lot don't seem to get injured at a higher rate than those who execute fewer plays.

3. Our next picture shows a similar lack of correlation, this time between defensive plays per game and the rate of opponent offensive injury. This idea would be that if an opposing defense is really bad, your offense gets more plays, and might get hurt more frequently. But the data shows nothing that looks like a relationship.

4. Now it's officially interesting. When we look at the rate of defensive injury against offensive plays per game, there is our most significant positive relationship. A correlation of 0.39 is way more than we have seen in the other three situations, and it's also the only one where there is a clear incentive to fake injuries.

Taken in isolation, you could argue the fatigue theory. But it's tougher to make that argument when you don't see anywhere close to the same relationship in all other situations. The only players who show a substantial increase in injury stoppages as number of plays increase are opposing defenses.

To me, that's pretty suspicious. Either opposing defenses are the only ones who suffer from fatigue-related injuries, or maybe some of the injuries aren't injuries at all.

But is this a pattern over time? Or just statistical happenstance in 2014? Later this week, part II of this article will examine the last five years to see if this is a consistent pattern, as well as what else we can observe about injury stoppages.

Bonus: The Jevon Kearse All-Stars

One last thing I did with this data, after pulling it together, was dig through and sum up all the specific players who sustained injuries in a game this season.

I wanted to look into it because I was really interested in what I’ve termed the "Jevon Kearse All-Stars." It may just be a bad memory on my part, but one of the things I really remember about Jevon Kearse’s tenure with the Eagles was his tendency to hurt himself and fall to the ground like he got shot. I feel like his injuries always looked more serious than they actually were. It’s possible I’m misremembering, and if so I apologize to the Freak. But with that said, here were the leaders in injury stoppages in the NFL this year:

• Jonathan Goodwin, NO (5)
• Vontaze Burfict, CIN (4)
• Ryan Clark, WAS (4)
• Marcus Gilchrist, SD (4)
• James Ihedigbo, DET (4)
• Johnathan Joseph, HOU (4)
• Jason Pierre-Paul, NYG (4)
• Rodger Saffold, STL (4)

Now I’m not accusing these guys of faking injuries; these just happened to be the guys with the most injury stoppages in the play-by-play data (excluding special teams, which most of these guys don’t play anyway). Jonathan Goodwin: your Golden Ace Bandage Trophy is in the mail.

Jared Cohen is a contributor to EaglesRewind.com and the author of the book How I Got on Jeopardy … and Won. He can be reached on Twitter @jaredscohen. If you have an idea for new research or an interesting take on a football subject, you can send your guest column idea to us at Contact Us