There's a statistic going around the intertwitterwebz that Bengals running back BenJarvus Green-Ellis has gone 354 consecutive attempts in the regular season and postseason without a gain of 20 yards or more. That game was October 19, 2010 against the Green Bay Packers when Green-Ellis burst for a 33-yard touchdown run. However during that same stretch that Green-Ellis hasn't gained a 20-yard run or more, the running back has also scored 15 touchdowns -- for whatever that meaningless stat means.
In an attempt to clarify a running back's performance without the required if/and statements regarding an offensive line, which is like saying how man can achieve space travel without the burden of oxygen, Pro Football Focus devised the Breakaway Percentage which "tries to measure how much a defense needs to worry about the running back because of his ability to break a big play."
The percentage is calculated by taking the yards gained on runs over 15 yards and dividing it by the player’s total rushing yards. So while it certainly helps to have a good line in front of you, game-changing running backs can shine through regardless.
Makes sense if not overtly simplistic. According to their formula Green-Ellis has generated one run of 15 yards or more and during that run he gained 19 yards, which accounts for 6.6 percent of his runs. Their qualifications are based on 30 or more rushing attempts through week four, therefore Green-Ellis ranks last among those running backs with at least one 15-yard run.
It's great that there's the focus on long runs. This offense could totally use more 20-yard runs, instead of a running back concentrating more on ball security.
The one caveat is that Cedric Benson ranks dead-last without a single 15-yard run.