Source: AP (via Yahoo)
In short: Melvin Mora was asked to play center field in favor of Miguel Cabrera at third base, and declined.
"If it was Edgardo Alfonzo playing third base, I keep my mouth quiet. I respect Edgardo. I (am not saying) that I don't respect Miguel Cabrera, but I respect Edgardo because he's played a long time more than me as a third baseman. He deserves to play that position before me."
Interesting way to look at it, I guess. I'm fine with him not playing because I couldn't care less about the WBC at this point other than seeing some baseball games, but to be fair, if I have a situation with Melvin Mora and Miguel Cabrera, I think I'll ask Mora to play center too. He's done it before.
He didn't rule out playing if he's slotted at third base, but that would seem unlikely.