Do We Need a Stinkin' Bullpen?

Lately I've been seeing a fair number of people take the position that the Phillies' acquisition of Cliff Lee won't really do much for them in 2011 because their bullpen is still weak. As David S. Cohen pointed out yesterday, the Big 4 are historically durable and have tended to go deep into games, so it's unclear how many innings the Phillies' relievers will even need to pitch, either in the regular season or the postseason. But even if the workload issue were set aside, would a strong bullpen really be that crucial anyway?

To be clear, I'm not suggesting that the strength of a team's bullpen isn't important - of course it is. Logically, scoring runs is 50% of baseball, while preventing runs is 50%. Pitching comprises the majority of the latter 50%. Relief pitchers account for about one third of a typical team's total IPs. So you'd expect the bullpen to make up about 10-15% of any team's formula for winning. Having an edge in that 10-15% share can make a real difference.

But some commentators go a lot farther than that. As I understand them, they seem to think that having a top-notch bullpen doesn't just give you an edge, but is also a necessary condition for winning a World Series. In other words, they think that if you have the disadvantage of a mediocre bullpen, then it's impossible to compensate for that by having even greater advantages in other areas of your team (like, say, the rotation).

That seems wrongheaded. The following is highly unscientific on a number of different levels, but here are the League ERA rankings of the bullpens of every team that has made it to the World Series since 2000.

Winners are in bold. Average league rank for winners' pens was 4.4. For losers' pens it was 4.1.

Again, I know this is unscientific, but just from eyeballing these numbers, it sure doesn't look to me like a mediocre bullpen is that big of a drag on your team's chances. I'm willing to accept that a bullpen might be disproportionately important - that it might comprise more than 10-15% of your team's formula for winning, or that it might be more than 50% as important as your rotation. But it's still a sliding scale. The better your rotation (or lineup or defense) is, the worse the bullpen you can get away with.

And the Phillies' rotation in 2011 is likely to be awesome. If it in fact pans out, then that awesomeness would be offset somewhat if the bullpen were to turn out to be mediocre or bad. But it isn't necessarily the case that the Phillies can't win with a subpar bullpen. If the rotation reaches a certain level of awesomeness, then it won't matter if the bullpen is mediocre.

Of course, all that just raises the question of whether the premise is even right to begin with. Do we really know that the Phillies' bullpen will be mediocre or bad? More on that after the jump.

A lot has been written about how teams shouldn't spend their offseasons targeting middle relievers, because the performance of middle relievers is so volatile. There are a handful of ace relievers out there who are dependably great every season. But aside from them, there's just no way to tell who's going to be good from one year to the next. All the teams are just out there throwing dice.

If you believe all of that, and I think most of us do, then the necessary corollary is that there's not much of a basis for downgrading the Phillies' chances based on their supposed bullpen weaknesses (nor is there much cause for celebrating the bullpens who happened to do well last year). For instance, from 2007-2009, the Giants' top relievers posted the following xFIPs: Wilson 3.46, Romo 3.78, Casilla 4.57, Ramirez 4.46, Affeldt 3.79, Lopez 4.64. With the exception of Affeldt, they all pitched great for the Giants in 2010. I don't think it would be fair to call that a fluke, but I do think they're equally as likely to fall back to the pack in 2011 as they are to maintain the results they achieved in 2010.

The 2011 Phillies' relievers posted the following xFIPs over the past three seasons: Lidge 3.89, Madson 3.29, Contreras (2010 only) 3.43, Reyes 4.11, Herndon 4.31, Bastardo 4.59. How will they do in 2011? Got me. But they don't look any worse coming into this year than the Giants' bullpen did coming into last year. And there's no point in worrying about it, because the team has no control over it, and nothing they do short of trading for, say, Matt Thornton is going to change that. So just sit back and let it ride.