Explanation:

Each individual rush is considered on it's own, and measured by it's "success." A run is considered successful if it gets 40% of the yardage needed to move the chains on first down, 60% of the yardage needed on second down, and 100% of the yardage needed on third or fourth down. This is a much more accurate overall picture of how well a running back does in a game than just the total yardage or ypc averages because it ignores big run outliers that can skew those kinds of stats

Stats after the jump. (LenDale White had two carries.  One was successful and one wasn't.)

I love it that CJ can go under 40% success and still rush for 151.