We're just a few games ahead of Pitts and Miami so I don't see how you can rule out McCutchen and Stanton. Stanton's having the best year, he'll probably win. Goldy's done with an injury so scratch him.
Miami is 1 game over .500 and -18 run differential. They are going to finish around .500. Pittsburg has a 0 run differential and should finish close to .500 as well. Sure Stanton can still win but if a deserving candidate emerges on a playoff team the MVP should go to that player. And right now Upton and Puig have that going for them.