They said he was pouting about being the closer. He wanted to get some stats to get a better contract next season so I don't think it's inconceivable that he was tanking to get out of town to a better team.
It's not inconceivable, but I really doubt that's the case.
Just as hitting is contagious, a winning attitude is, too. Maybe being on a winning team helped him. It could also be that he's more comfortable w/ the closer's role. It could be a lot of things.