It's one of those little quirks of the trading process that you probably know about, but may have forgotten: when a player is traded in the middle of multi-year contract, that player has the right to demand a trade during the following offseason. Now, this isn't a T.O. style "demand" - there's actually some significant weight behind the demand (if the player decides to use it) in that team either has to trade the player (although the player doesn't get to determine where) or grant the player free agency in mid-March.
Players don't demand a trade after they've been traded very often, but it does happen. Sometimes players will use the threat (or possibility) of demanding a trade as a tool for obtaining a contract extension.
That's all possible, but I don't think it's going to happen with newly acquired Ron Villone - who contractually has the right to demand a trade after this season. The Marlins mark the 9th team that Villone has played for (just in the Majors), so he'd probably be happy with a little stability. Plus the Marlins will be happy to keep an effective reliever, who's only set to make $2 million, so it's something of a happy marriage.
Side note: the Sentinel article linked to above mentions Delgado's "tender" elbow. I'm failing to understand just how tender his elbow is - and if it's such a problem (and WQAM is reporting that Delgado won't play until at least the weekend), why don't they just put him on the disabled list? In some ways this feels like the issue the Fish had with Luis Castillo earlier in the year; Castillo was hurt, missed about two weeks of action, but was never placed on the DL. In Castillo's case then and in Delgado's case now, it effectively reduces the bench and Jack McKeon's options by one bat. That's not my favorite thing in the world.
What would be better: 13-days without Delgado (or Castillo) and a 24-man roster, or 15-days without Delgado and an extra bat called up from Albuquerque? I'd side with the latter option, as another option would have been nice for the past week or so. I suppose the Fish have gone into both of these situations assuming that neither Delgado nor Castillo would be out nearly as long as they've been. But in that case, why not just make a retroactive move and free up a spot for someone else - if only for a few days?