According to Marty Noble, Nelson Figueroa is likely to make the Mets' Opening Day roster as the swingman, filling in as a long relief specialist, spot starter, Perez-mopper, and whatever else Jerry Manuel can dream up. Nothing is set in stone, and Figueroa didn't do himself any favors by allowing seven runs in 2.2 innings against the Marlins on Friday. His flawless ERA ballooned to 5.91 while his chief competition for the last bullpen spot, Fernando Nieve and Pat Misch, pitched two scoreless innings apiece.
Misch might be the most interesting candidate here, though he's probably the least likely to actually make the team out of spring training. His peripherals this spring are meh--eight strikeouts and six walks in 12 innings--but he's been a ground ball machine, logging 20 grounders to just six fly ball outs. He's never really been an extreme ground ball pitcher in the minor leagues, but his ground ball rate has gotten better over the years.
Assuming Hisanori Takahashi makes the team, he and Pedro Feliciano will give the Mets two lefties in the bullpen already, plus another two in the starting rotation. Would five lefties out of 12 pitchers be too many? I'm not sure that's the relevant question. More importantly, is there a righty who makes more sense--i.e. who is a better pitcher--than Misch. Figueroa is probably better. Nieve might be, but only marginally so. None is fantastic, but given Figueroa's mighty effort down the stretch in 2009 he clearly has the best recent performance on his side. He's also the oldest by far, but we're not talking about signing any of these guys to a long-term contract, so the only attribute that really matters here is effectiveness.
The swingman is often considered the last spot on the pitching staff, but a solid one can really make a big difference. Think about the quality innings a guy like Darren Oliver gave the Mets in 2006, particularly in extra innings and in the Steve Trachsel bed-shitting against the Cardinals in the NLCS that year. File this one under the difficult-to-quantify, but a guy who can come in and pitch four or five innings and "save" the bullpen can prolong the usefulness of the rest of that bullpen and keep them fresh for the games that are within reach.