Uh I would be upset with the Yankees in the first place, they are the adversary.
A corrollary, should I have gone and helped the nazis, because I was mad about Patton being reprimanded.
Nah man, because the Nazis aren't embracing your ideals. But the Free Czech resistance is, so you might end up fighting with them.
In retrospect, those 6 players that you loved didn't get picked up by the Yankees, but rather the Boston Red Sox. So, the Red Sox now have the 6 main players (issues/reasons) that you are a fan of baseball. Sure, they play against the Mets (interleague play) but they also play against the Yankees more.
So, I guess the point is that this particular person is more loyal to players (ideals) than he/she is to the team (political party) since the player transcends the team. Just like conservative ideals, freedom and liberty transcend (and are ignored by) the Republican Party.