I am thinking more along the lines of an internal option. The Mets have some options in the minors that may produce better than Zambrano but they weren't going to get the chance up until now due to the politics of the Kazmir trade.
As far as a trade goes I would think that there are a shortage of arms out there right now. Maybe there will be something available near the trade deadline but I don't see it happening soon. If it comes down to making a lateral move (trading for someone to fill Zambrano's production) I don't think there is any need. Mets pitching at the minor league level is deeper than it is given credit for. It gets dogged because it lacks top tier talent other than Pelfrey (Humber, maybe).
Maine has a good swing for a pitcher but on anything that moves, he has no chance. And if it's a fastball, it has to be up in the zone. Basically, the pitcher has to hit his bat. - Mike Pelfrey