Some people are already saying that McCoy is progressing faster than Westbrook, and there's some rudimentary evidence to cite on that front.
For starters, McCoy has shouldered a greater burden than Westbrook in his first two seasons. In 2002, Westbrook barely got on the field. Then in 2003, Westbrook spent most of his time as a situational player. He was amazingly explosive in that role, amassing 13 combined touchdowns in '03 on runs, catches, and returns even though he was only getting about 12 total touches a game.
McCoy, on the other hand, was forced into a main role in the offense almost immediately during his 2009 rookie season — in which he amassed almost as many touches as Westbrook received in his first two years combined. In 2010, his second year, McCoy has taken full command of the starting running back spot, something Westbrook only did in year three.
Does that mean McCoy has progressed a year faster than his predecessor? Not necessarily. First of all, McCoy was coming from the advantage of a big time college football at the University of Pittsburgh. Westbrook, on the other hand, was making the leap to the NFL from D1-AA at Villanova. He was fighting an uphill battle to even make it in this league.
Second, we don't know that Westbrook couldn't have taken on a bigger load earlier like McCoy did. #36 entered the league when the Eagles already had two capable backs in Duce Staley and Correll Buckhalter. Andy Reid didn't need to rush him along like he did with McCoy.
So, all that aside, what if we do want to compare the early Westbrook years with what we're seeing from McCoy? Ultimately I think you have to compare Westbrook's 2004 season, his first as "the man," to McCoy's 2010. And looking at the actual numbers, you can see a pretty obvious trend:
Clearly, the stats don't show that one player was drastically better than the other. In fact, the two players had remarkably similar beginnings to their first starting season, both in terms of workload and production.
We can come back to this comparison as the year goes on. One key note to remember is that Westbrook fell off this rather strong pace as the 2003 season continued. Obviously he was still very effective, but if McCoy follows the same route, we might see a similar decline over the course of this season as he wears out and teams focus more on stopping him.