Every good starting rotation needs 7 starters. Your first three are locked in, while your last two spots can rotate among three pitcher throughout the year, with one in reserve for the inevitable injury. Now, the Mets have the #1 slot filled, with Johan. Pelfrey has battled enough this season that I feel reasonably comfortable that he can be at least a good #3. Obv

So, that leaves two slots to be filled at the end of the rotation. Candidates for those spots include: John Maine, Oliver Perez, Bobby Parnell, Fernando Nieve, Coney Island native Nelson Figueroa, Jonathon Neise, and maybe even Brad Holt. Now, what do these pitchers all have in common? With the (notable) exception of Perez, they're all making at or close to the league minimum. So, if one of them wins the other spot behind Perez, the Mets will be spending $12 million on two rotation slots. With the average Major League salary about $3 million, not the ideal way to spend your resources, but not as bad as $12 million on one slot.
Now if only he could stop walking everyone on earth...