NFL Injury Analysis: Are Leg Injuries More “Questionable” Than Others? (3 of 4)

November 9, 2010 - by John Ezekowitz

The third post in a series presenting our analysis of NFL injury reports and the likelihood of injured players to play based on injury type, status, and position.

Our last post examined players who were listed as “probable” on the injury report. This one looks at “questionable” players and the likelihood that they will play.

One informal NFL rule of thumb about questionable players is that they have about a 50-50 shot of playing. Based on injury reports from 2008 and 2009, we found that the average questionable player actually plays 57.8 percent of the time.

Just as with probable players, there was a considerable variance in the likelihood of playing across positions and injury types, ranging from 44% to 70% likelihoods to play. Furthermore, the odds of playing relative to the mean odds of playing were not as evenly distributed as with “probable” status injuries. There were several outliers for injury types, which are summarized in the tables below.

Questionable Playing Percentages: The Best

Injury Type	Percent Played
Illness	70.91%
Undisclosed	70.21%
Hip	65.31%
Shoulder	64.86%
Toe	64.15%

As you can see, two catch-all categories are the most likely types to play. Both illnesses and “undisclosed” are non-specific, but players that are listed in these two categories are almost a third more likely to play than the average questionable player. Shoulder injuries, which were one of the “probable” injuries associated with higher than average playing rates, also appear near the top of the list here.

Questionable Playing Percentages: The Worst

Injury Location	Percent Played
Hamstring	53.15%
Arm	52.94%
Quadricep	51.28%
Disciplinary	46.67%
Calf	44.12%

The least likely injuries to play are even more interesting. Here we see definite patterns developing. Both calf and hamstring injuries, two of the least likely injuries to play, were also among the least likely “probable” injury types to play.

As both of these injuries are very common, this is an interesting trend, especially for fantasy owners. More generally, leg injuries appear to hold “questionable” players out significantly more than other injuries, as heel and achilles injuries are also well below the average for likelihood of playing.

Questionable Playing Rates By Position

The next table shows the relative likelihood of playing for “questionable” players by position:

Position	Percent Played
Defensive Tackle	65.38%
Linebacker	61.11%
Center	60.00%
Defensive Back	59.54%
Running Back	59.43%
Tackle	58.59%
Defensive End	57.25%
Quarter Back	56.60%
Tight End	54.65%
Wide Receiver	54.55%
Guard	53.45%
Fullback	49.40%

As you can see, the spread by position is far less dramatic than the spread by injury type. We might hypothesize that when all types of injuries are aggregated across a position, the combined likelihood is closer to the overall average. This warrants further study.

In contrast to the “probable” likelihoods, the “questionable” likelihoods for defensive players are higher than the average. This seems to imply that the differences between “probable” and questionable” injuries for defensive players (especially d-linemen and linebackers) are not large. In fact, “probable” linebackers are only four percent more likely to play than “questionable” linebackers.

Finally, it is interesting to note that whereas “probable” quarterbacks were the most likely position to play, “questionable” quarterbacks play at the overall average rate.

Our next post will explore in-depth analysis of players listed as “doubtful” on NFL injury reports.