Correct me if I'm wrong but this is a very good player, just not a superstar bat. To answer the IP, his .240 average might be due in part to park and league factors but I would think he's a bit better than that, just not a consistent .300. He's probably capable of a few breakout seasons here and there in counting stats depending on the lineup around him, but not long term consistent slugging because frankly none of his hitting ratings are elite... he'd be more of what you want if a few of them were in the 80s.
I would guess his ratings increased in season 7 because that was his jump to the majors, playing time, and likely improved coaching. His average dropped from facing much better pitching over the long term.
Ultimately the guy is an all-round good player, but a lot of his valuable ratings are in categories that don't really improve his hitting. A bit of a letdown from a first overall draft pick, unfortunately.