The issue with Correa is that players signing big $$ contracts always seem to press during the 1st year of the contract. Expect better going forward.
The issue with Buxton is simple: For the 80 games (or so) he plays, he's elite. This team simply can't afford a PT player. If it were up to me, I'd offer him an injury settlement of his contract and move on.
The issue with the "3 true outcomes" approach to hitting may not be solved soon within the organization, but it can be solved via trade in the short term. Whenever the team is trading for offense, it should look for players closer to the Arraez model than the Gallo model. I know - easier said than done.
I do believe the team has not yet figured out Target Field and used it to it's advantage. Target Field is a pitcher's park when the game time temps are under 60 degrees; it's a hitter's park when the game time temps are above degrees. The other teams seemed to have figured that out. Too bad the Twins haven't.