I have long wondered why there isn't some sort of system that does that. The more advanced projection systems adjust for team defense. FIP works very well when your sample is small (like in a half season) because luck plays a huge role in the results of balls in play. If your sample size is huge (a career), ERA pretty much is all you need. In between you want to give the pitcher, the fielders, the park and luck their fair share. Here is an excellent discussion on the topic: http://www.tangotiger.net/solvingdips.pdf Page 18 they come to the conclusion: "So, what we are saying is that we have a 10/6/4 split between pitching/fielding/park, in, that order. Luck plays a part, and that is dependent on the sample size. When n=1, it's almost all luck. When n=1 million, luck is not involved." Over 700 balls-in-play (about a season), they break it up like this: luck : 44% pitch: 28% field: 17% park : 11% This is 8 years old, though, so there might be better stuff out there but clearly, luck still plays a significant role over a season or less.