When it comes to running the football, there’s a pretty simple concept, supported by data, that says that the more big bodies there are on the field, the more difficult it is to run the ball. We explored this concept yesterday utilizing Pro Football Focus’s compilation of all 73,000 or so qualified carries over the last five years.
One component of that statistical analysis that I did not highlight in my previous article was the concept of expected yards per carry, as determined by the number of carries and the personnel faced on those carries for a given runner. PFF, for example, found that the average run against a base defense gained 4.2 yards in their five-year sample.
Though naturally far from perfect, I find this to be an interesting and enlightening measurement of tangible running success, as it helps to neutralize the benefits gained by runners who more often get the opportunity to run against sub-packages, and gives more credence to runners more liable to face base defenses.
In Chip Kelly’s spread offense, for example, Philadelphia Eagles running back LeSean McCoy had an expected YPC average of 4.4 due to the frequency with which defenses played the Eagles offense with sub-packages.
Willis McGahee, on the other hand, is not only geared toward between-the-tackles running, but also played on an offense with questionable quarterback play last season, and thus faced more base defense when he carried the ball. As a result, his expected YPC average was just 3.8.
As it turns out, the Pittsburgh Steelers’ two backs, Le’Veon Bell and LeGarrette Blount, find themselves on the opposite ends of the expected YPC versus actual YPC differential.
Blount, who obviously played for the New England Patriots last season, nevertheless had an expected YPC of just 3.9, suggesting that he regularly faced only four or less defensive backs, yet he averaged 5.2 YPC, including the playoffs, which gave him a league-leading 1.2 YPC differential.
On the other hand, Bell found himself in the bottom 10 of the 47 qualified running backs in YPC differential. His expected YPC was just 4.0, but he only gained 3.5 YPC during the season, giving him a differential of -0.5.
The data is just the data, of course, and only tells part of the story. PFF understands this, which is why they graded him favorably as a runner last season despite his below average YPC.
The site graded the offense’s run blocking as a whole quite poorly in fact, 20th in the league, so that goes a long way toward explaining why Bell is viewed favorably despite the seemingly poor per-play performance.
The Patriots were graded only 17th in run blocking though, to be fair, and, as mentioned, Blount went on to lead the league in this admittedly artificial statistic, largely thanks to his great success on first and 10 carries.
He averaged 5.83 yards on 95 runs from first and 10, including carries of 12 and 23 yards when the Patriots played the Steelers last year. He now brings that early downs prowess with him to Pittsburgh.