It's probably a little immature to root against a player but I'm sure we all have a player we absolutely despise for no reason, just take joy in them failing for either reasons to benefit out team or because we simply don't like them.
On the Mets, it would easily be Ruben Tejada because well, he sucks and id much rather see a bag of balls at short stop.
Generally? I root against Max Scherzer, the fact that he turned down a monster extension pisses me off, I'm sure you could make the case that he simply doesn't like Detroit but regardless, the greed ticks me off.
Robinson Cano as well, lazy ball player who was awfully greedy this offseason, pretty much the same reason as Cano.
Cole Hamels as well, simply because as a bitter Mets fan, he called us choke artists and I laugh every time he gets bombed by my Mets, it's a rivalry thing I suppose.
Before I get criticized, don't pretend that you don't have a few players like I do.