McKnight only has 22 carries on the year, yet has the longest run we've had since Week 1 of 2009. He'd have a lot more of those if they bothered to give him the ball more often. But we prefer a "power" running game that picks up less than 4 yards per carry and breaks 2 or 3 20+ yard runs each year.
McKnight leads the team with 6.0 yards per carry. Yes, it's small sample size. But his distribution of runs is exactly how the guys that average 4.7+ yards per carry wind up with those numbers. They get stopped for short gains just as often as Greene does. But those well blocked runs where Greene gets 9-15 yards, they get 30. And that's why they average almost a full yard more per carry than him.