...because of the roster the FO surrounded each of them with.Value in terms of WAR is linear, but value in terms of "World Series Win Probability Added" is non-linear. If Mike Trout and Mookie Betts both go two for five with a home run and a double, they've added the same WAR, but Mookie increases the chance the Sox win the world series by, let's say, 0.2% whereas Trout adds exactly 0.00% (since the Angels have been eliminated).
Rewarding/ docking a player for the roster he's on in a discussion of who has been the most valuable individual player still doesn't make sense to me.
The boring answer is Trout, especially because it's been four straight years he's been the "boring" answer. But I can't see any way he hasn't been the most valuable.