If you look at the closers thread, you can see that the case could be made that BJ Ryan is having just as good of a season as Papelbon is. A closer winning ROY has to have one of two things happen...one being there isn't any real competition for it (IE Street last year), and two they have to be having an out of the world type season anyway. Since, as of now, Ryan's numbers are comparable to Papelbon's, I wouldn't say that Papelbon is the favorite of anything right now. It's very close between him and Liriano.
I do know this, if Liriano pitches as well as he has tonight, or even remotely close to it, there's no debate at all. He'll be ROY.