Early in the 2010 season, the Orioles have played a very difficult schedule. They have faced the Rays (21-7) six times, the Blue Jays (17-13) three times, the A's (15-14) four times, the Mariners three times (11-17), the Red Sox six times (15-14), the Yankees six times (19-8) and the Twins once (19-10). Even if you take the Orioles games out of those records, only the Mariners (8-17) and A's (12-13) are teams playing below .500 against the rest of baseball. Anecdotally, it also seems as if the Orioles have faced exceptionally good starting pitchers almost every night. Does the data support that perception? In a word, yes.
Opponents' starters have absolutely dominated the Orioles this season. In 29 games, starting pitchers have thrown an average of nearly 6 2/3 IP per start, allowing just 7.8 H/9, 2.7 BB/9, and 6.3 K/9 on their way to a 2.27 ERA and 1.16 WHIP. In other words, the Orioles offense has turned every opposing pitcher into one that would rank T9 in the American League in ERA. Who would that pitcher be tied with? Zack Greinke. You'll also notice from that list several pitchers that have made multiple starts against the Orioles, including A.J. Burnett (5), Matt Garza (7), Jeff Niemann (8), and C.C. Sabathia (11).
Taken in aggregate, starting pitchers in the American League have pitched 2,217.1 innings against non-Orioles offenses with a 4.44 ERA and 1.38 WHIP. Combined (including double counting all pitchers that have made multiple starts against the Orioles), the starter's the Orioles have faced have a 3.68 ERA and 1.25 WHIP in 762.1 IP against non-Orioles opponents. So, yes, the starter pitchers the Orioles have faced this season are significantly better than league average.