We don't know that. And I am in no way saying that I'm unhappy with Vazquez being called up. Given the choice between the two, Vazquez has always been my guy.
I have no way of knowing for sure, but I would be willing to bet that if Swihart had played well, which means the pitching staff had pitched well also, Swihart would still be up.
I think most people would agree with that, if they're being honest.