Analyzing Felix Jones’ Usage, Efficiency on Turf vs. Grass
About a year ago, I posted a study which showed that the efficiency of running backs does not change based on the field surface, even for runners of different styles, i.e. as a whole, small, quick running backs perform no better on turf as compared to grass. I floated out the idea that a running back like Felix Jones (and now rookie DeMarco Murray) might be superior on turf because his quick-twitch, speed-based game seems to be suited for a fast track. The evidence seemed to suggest otherwise.
Now that Jones has played three seasons in the NFL, his numbers on turf and grass are beginning to become statistically significant. Of the 38 games in which Jones has participated (including two playoff games), 26 of them have been on turf. On the chart to the left, you can see his efficiency on runs has remained steady regardless of the surface–he averages 5.3 yards-per-rush on both grass and turf. He has been a bit superior as a receiver while on grass, but this is likely due to a small sample size (14 receptions on grass, 58 on turf).
While the numbers related to Jones’ efficiency are no surprise, his usage statistics are another story. You can see that Jason Garrett has given Jones three more carries per game when the Cowboys have played on turf as compared to grass. This may not seem like a lot, but a roughly 30 percent increase over a sample size of 38 games is pretty significant. The probability that such a difference would be due to chance is small, meaning it looks as though Garrett provides the ball more to Jones when the ‘Boys play on what the coach considers a fast track.
That idea appears to be affirmed by Jones’ reception numbers as well, as he catches nearly twice as many balls on turf over grass. While Jones is the recipient of dump-offs from time to time, the majority of his receptions have come on screens or other plays designed to get him the ball in space. It really does appear as though Garrett assumes Jones is a more lethal player on turf.
Of course, the Cowboys play their home games on turf, and the team may be more likely to be winning late in home games over road games. When leading late in the game, additional carries are likely. However, in the 20 home games in which Jones has participated, the ‘Boys are just 11-9. That mark is very similar to the Cowboys’ 10-8 mark on road games in which Jones has played, meaning the idea of Jones’ “extra” turf carries coming from leading late in home games is inconsistent.
Ultimately, Garrett just needs to continue to feed Jones the football, regardless of the playing surface. The addition of DeMarco Murray via the draft provides the Cowboys with an insurance policy against a Jones injury. Of course, Garrett may have no choice but to give Jones or Murray plenty of touches on grass, since Marion Barber will be out of Dallas in 2011 and the head coach loathes Tashard Choice.