The Running Men
Are mobile quarterbacks like Colin Kaepernick more injury-prone than pocket passers?
By Omar Bashir and Chris Oates
Posted Friday, Feb. 1, 2013, at 9:45 AM ET
Conventional wisdom says a runner is more likely to get hurt than a stay-in-the-pocket statue. Just ask Joe Flacco, who told the assembled press on Wednesday that “quarterbacks like [Kaepernick] are eventually going to have to become mostly pocket passers to survive in this league.”As you’ll see in the chart below, regardless of how we sliced the data, there was no statistically significant difference in injury rates between mobile and conventional quarterbacks. Quarterbacks of both types tend to lose 11 to 14 percent of their starts to injury. Even without counting the thus-far injury-free Kaepernick, three of the four tests produced a lower injury rate for mobile quarterbacks. The gap, though, is small enough that a statistician would call it zero.It turns out that the only gameplay variable that explains injuries with any statistical significance is sacks. On average, a 1 percent increase in sack share—the percentage of plays called for the QB that end in a sack—is associated with a 2.6 percent rise in starts missed due to injury (0.7 percent standard error). This link holds when we use the career-wise dataset and when we use sacks per start instead of sack share.