I think he's at the peak of what he can do right now. Twenty-three percent of his balls in play are flyballs, yet 14 percent are clearing the fence. There's nothing in his swing that says he will consistently hit over half of his flyballs for home runs*, so I think his slugging is inflated. I also question if he's really a .300 hitter. Maybe I'm wrong, but .300 hitters who hit 54 percent of their balls on the ground and strike out 16 percent of the time seems out of line. So over a full season, I estimate that he's a .280/.330/.390 hitter. *ETA: Sixty percent of his flyballs are going for homers. Not even Adam Dunn has done that.