Justin Upton and Park Effects
I have a post up over on FanGraphs about Justin Upton, but it’s really more about home/road splits in general and how they should be used. Quoting the conclusion, but you should read it all to see why the conclusion exists:
Whatever you do, though, don’t just look at a player’s road stats and assume that it’s a window into his real talent level, with the difference between his home and road stats being a mirage of the park he played in. That’s simply not how home/road splits work.
A lot of people look at Justin Upton and think he won’t hit in Seattle because his road numbers suck. A lot of people look at the Mariners hitters from last year and think that they’re all actually good because their road numbers were good and their home numbers sucked, thus Safeco just screwed everyone over. Those conclusions are easy to draw. Those conclusions are not completely accurate, though, and you shouldn’t be willing to so easily use split data to come to such conclusions.
Justin Upton is better than his road numbers indicate. Jesus Montero, Kyle Seager, and Michael Saunders are probably worse than their road numbers indicate. You want to adjust for park effects, but do it correctly. Realize that Justin Upton won’t hit as well in Seattle as he does in Arizona, while at the same time realizing that Justin Upton is a good hitter who will likely be a productive offensive player no matter where he calls home.