Hmmm….I haven’t actually read up on park factors if they’re doing them in a more advanced way than they used to. Honestly, I think that’s a mistake at this point, as it’s a really complicated issue that takes extremely detailed data (that we don’t really have yet as far as I know, hit f/x and field f/x could probably give us what we need, though, but again, it’d be pretty complicated). Initially the purpose of park factors wasn’t to adjust players performance down or up, but rather to adjust the value of their performance down or up – if a place like Coors allows 20% more runs than a normal park, a player has to contribute to 20% more runs in Coors than a player in a normal park to give his team equal value towards winning.

If you want to really get into the details of “how does the park affect a players performance”, though….you have to know everything – park dimensions, carry of the ball in that park (and it’ll be different to different parts of the yard), vector of every batted ball, and calculate each batted ball’s expected outcome in a neutral environment and then sum those up for an “expected” amount of production. Not too easy. The way I currently do it is less scientific and more of an art – check out guys HR sprays to see what kind of hitter they are (pull, opposite field, whatever else), check out their FB/GB rates, and have an understanding of the park specifically. For example, we know AT&T suppresses HR’s to LHH’s a lot, but can help out gap power lefties like Fred Lewis. So my guess is Lewis is a bit worse than his stats suggest – between a slightly positive hitters park overall in AT&T and a big outfield that turns his singles into doubles and doubles into triples, he benefits, and doesn’t lose too many HR’s. On the other hand, knowing that our park suppresses HR’s to RF, I’m worried about Aubrey Huff.

Hope that helps and makes sense, feel free to ask if you want me to elaborate more on anything.