I disagree with those who say the Johan Santana acquisition eases the strain on the bullpen. While they may be needed less with Santana pitching than, say, a 41-year-old Tom Glavine, the same figures will be relied on again and again, and the strain on them will be just as much as it has been, with extra pressure to secure wins for Santana.
If all goes well this year, the Mets will have Duaner Sanchez for the 7th inning, Aaron Heilman (7-7, 3.03 ERA, 1 sv in 2007) for the 8th, and then Billy Wagner (2-2, 2.63, 34) closing games in the 9th. The biggest question mark is Sanchez, who missed all of last year after a car accident that left him with an injured shoulder in 2006. Last year, Sanchez never got back into playing shape, but this year, he is reportedly in great shape in spring training. Even more important about Sanchez's situation is that when a starting pitcher goes 7 innings, he will be able to split an 8th inning load with Heilman.
I've mentioned this before - I think Santana errs on the side of caution when it comes to his arm. That could result in a few starts where he goes just six innings. Last year, 13 of his 33 starts lasted just 5 or 6 innings. Couple that with an aging Pedro Martinez* and Orlando Hernandez in the rotation, and the bullpen could see plenty of work.
So the bullpen will be an important factor all season for the Mets (and every other team in baseball). Wagner will close games - there's no doubt about that. My fear is that he will get hurt, and the Mets will be left vulnerable. I expected more injuries from Wagner the past couple of years, and he's stayed surprisingly healthy. He'll be 37 this season...his body is going to break down sometime...hopefully it's not this year. Wagner's biggest contributions this season could very well be with his mouth - he becomes prime suspect number one for speaking his mind (after Carlos Beltran, though, it seems) now that Paul Lo Duca is gone.
For the first time in a number of years, Aaron Heilman hasn't been complaining about his role...it seems, for now, he has given up all hope of becoming a starting pitcher with the Mets...and by coming back this year, he might realize that by not rocking the boat, 2008 is a very real possibility for a world championship.
Besides Sanchez, the other key members of the bullpen are lefty Pedro Feliciano, who was 2-2 with a 3.09 ERA last year. Lefties hit just .168 against him. Scott Schoeneweis will be back, fresh off his appearance in the Mitchell Report - and he had a very disappointing 2007 season (a 5.03 ERA tells the tale). Sidearmer Joe Smith will be a factor at some point this season, but after a great first half of last season (36 IP, 2.75 ERA), he pitched just 8 innings in the second half of the season, and was not effective (6.48 ERA). Jorge Sosa was a pleasant surprise for much of the season, doing good work filling in as a fifth starter, but you don't know what you're getting from him this year. He might be the 2006 Darren Oliver/2007 Aaron Sele long-relief type in 2008. And the Mets signed Matt Wise, late of the Brewers, who is coming off a decent year, but nothing special.
The Mets have some arms in the bullpen, and I think they'll be OK when they have to use their relievers. The example of Joe Smith illustrates, though, what overwork can do - he was a rookie last year, and was overworked in the first half. The Mets paid the price for that in the second half, and Willie Randolph lost confidence in the reliever.
Someone will certainly surprise out of the bullpen this year, and someone will certainly disappoint. It's the same story every year. What the Mets need is consistency from the trio of Sanchez, Heilman, and Wagner. If the Mets can get leads to those guys, and they pitch like they did two years ago, the bullpen will be a strength, and not such a question mark.