Starters v. relievers

Jerry Remy noted last night that the Tigers' bullpen has a better ERA than the starters, and that getting to the Detroit bullpen isn't the same advantage as it is against other teams. That raises the question: how do the Red Sox starters compare to the bullpen? Well, here are the overall numbers:

            IP    HR/9   H/9   BB/9   K/9   WHIP   ERA
Starters   683.2  1.33   9.77  2.96   6.77  1.41   4.91
Relievers  354.2  1.04   9.07  3.15   7.05  1.36   4.11

As you can see, the guys we're trotting out every fifth day are not getting it done, compared with the guys who have to come in and clean it up. They are giving up more hits and homers, and even with less walks have allowed more base runners. The home runs are the real killer here, especially with those extra baserunners. Keep in mind that these numbers are adjusted for innings pitched, so while David Pauley's 7.88 ERA might seem like it will unfairly skew things against the starters, he's only pitched 16 innings and hardly effects things compared to Josh Beckett's over 150 innings of 5.00 ERA.
A closer look reveals some even more surprising results. Take a look at how everyone's favorite whipping boy compares to the starters:

             IP     HR/9  H/9   BB/9   K/9   WHIP   ERA
Starters     683.2  1.33  9.77  2.96   6.77  1.41   4.91
Rudy Seanez  44     1.23  9.41  4.09   8.8   1.5    3.89

That's right folks, the sox prospects actually improve when Rudy Seanez takes the mound.
One final note – here's how the numbers stack up for the heir apparent to the closer role vs. whipping boy number two:

               IP    HR/9   H/9   BB/9   K/9   WHIP   ERA
Julian Tavarez 59.2  1.22   10.49 3.8    5.43  1.58   4.98
Craig Hansen   27.1  0.66   10.96 2.66   6.91  1.5    5.27

Somehow, despite giving up twice as many jacks, walking more and striking out less, Julian Tavarez has a lower ERA than Craig Hansen. This may be where DIPS comes in: when comparing pitchers, look at defense-independent stats first, they remove more of the luck from the equation. Homers, Ks, and walks are all controlled by the pitcher. Hansen dominates Tavarez here, but he's given up more hits and has a worse ERA. Who is likely to be the better pitcher going forward? Obvious.