I can't upload the screen shot, but to me Correa's positioning seemed within the rules, unless the camera angle behind home plate was slightly off. The line goes directly across second base, corner to corner, and Correa's feet appear to be slightly to the SS side of the base. His body is leaning to his glove side, but, to me, his feet, and thus his positioning, appear legal.
This is a situation where several different people's judgment came into play; the fielder, the umpiring crew, the opposing manager and, upon appeal, the umpire in the review office. The HP umpire, looking directly at Correa did not call it. I know his focus is on the P, but pre-pitch he can see fielder positioning. The 2B umpire, standing six feet from Correa did not call it. The opposing manager, from the 3B dugout, at field level, makes a challenge and the play is reversed (good for him).
MLB has dropped the ball on this rule. They need to take the judgment calls out of this and paint a stripe behind second base before this decides a more important game.