It's also possible he plays better in his home park then at rival stadiums. He plays in a hitter park but he also plays in the NL west so he has plenty of games in other hitters parks.
He plays in Colorado, and Houston a bunch of times, also very good away parks to hit in. What is every away park a pitchers park?
My point is just because he hits less on the road doesnt necessarily mean he's a product of a hitter park, he may just be more comfortable in his home stadium.
There are plenty of hitters parks in the NL that he can inflate numbers, even better than Arizona. I'll take my chances with his upside anyday, he doesnt hit cheap homers where ever he plays.
I'm not saying hes an MVP, but to say he is barley an upgrade over Duda, Baxter, and Kirk, even with those splits is laughable.