With good reason, the Orioles bullpen has been the target of much wailing and gnashing of teeth in the early going. So imagine my surprise today when I checked the pitching splits page at baseball-reference.com and saw that Orioles relievers (4.70) have a lower ERA than do Orioles starters (4.75)! How is this possible? There are two big reasons:
1) Brad Bergesen. He's made three starts, combining for 10.1 IP and a 12.19 ERA. Strip out those three starts and the rest of the O's starters have a 3.97 ERA over 99.2 IP, which is not too shabby at all.
2) Inherited runners. As of April 26, O's starters have passed off 16 baserunners to the bullpen. Nine of them have scored. The league average rate for inherited runners scored is 34% (across all situations; it is possible that O's starters have biased their inherited runners toward high run expectancy situations like second and third with no outs). If O's relievers could acheive that league-average percentage, the starters would have been charged with 4 or 5 fewer runs, bringing their collective ERA to 4.34 or 4.42. Control for Bergesen (who, ironically, has only had 1 of his 3 bequeathed runners score) and the top four O's starters have an ERA in the 3.60 range.
As for the more skill-dependent numbers, Orioles starters are performing better than their relief counterparts there, too:
K/BB ratio: 2.40 for O's starters, 1.85 for O's relievers
HR/9: 0.90 for O's starters, 1.17 for O's relievers
So, yes, the Orioles rotation has been much better than the bullpen, especially when you look at the numbers without Brad Bergesen. With the offense finally scoring a few runs this weekend, the bullpen needs to start pulling its weight to get the O's a few more wins.