I don't think he is apt to have another .390 year. I do think he's a lot better than he hit last year, when he had a 3% walk rate and a 25% K rate. Like you, I think that's atrocious and we can't have that kind of non-production at third.
But I don't think he's that guy. I like the path his bat takes through the hitting zone when he's right. He stays on plane for a long time. Having said that, the key word in there is "long". He is long and prone to Ks, certainly moreso than the usual line drive hitter, who has a quick stroke and waits on the ball. He started trying to hit the ball out of the ballpark and got messed up. He's more of a 15 homer - 40 double kind of guy. He needs to get back to what was working, which was a little shorter swing and waiting, going the opposite way and not pulling the trigger so early on breaking balls. I think he can and he's going to have the right hitting coach.
Defensively, he's not particularly athletic and a little stiff with limited range. He works hard and catches what he gets to, though, rarely makes a mistake, anticipates well. He makes the plays he needs to make, no more.
And if there was ever a clubhouse in need of fire, it's this one. He's a bit of an asshole. I like that.
I don't think he's a .321 hitter. I think hes a .300 hitter with gap power.
So that's my almost entirely subjective take. I did use stats, but I used them differently than you did. I had a sense of what was going on, then buttressed it with stats. Sometimes I'm surprised. I don't think I am here.
Not everything that can be counted matters, and not everything that matters can be counted. -Albert Einstein