It's Chen vs. Santana tonight

Orioles left-hander Wei-Yin Chen is seeking his third consecutive win tonight since coming off the disabled list. He also could intensify the debate over which Orioles starter qualifies as the ace. Is it Chen, Chris Tillman or Miguel Gonzalez? Chen has allowed two runs and 11 hits in his last two starts covering 13 1/3 innings - both against the Rangers. He's posted seven quality starts among his 10 outings, and he was headed for another on May 12 with five scoreless innings in Minnesota before straining his oblique. He came within an out of recording one in his first start of the season. Chen has won his last three decisions and five of six. There just happens to be a two-month stint on the disabled list that breaks up his streak. Left-handers are batting .197 against Chen, compared to .273 by right-handers. Billy Butler is 5-for-9 with a double, triple and two home runs against Chen. Royals starter Ervin Santana is 4-5 with a 5.36 ERA in 13 games against the Orioles. Brian Roberts is 11-for-29 with a double and two homers against him. Nick Markakis is 11-for-37 with five doubles, three homers and 10 RBIs. J.J. Hardy is 4-for-13 with two homers. Chris Davis only has five hits in 25 at-bats, but that includes two doubles and three home runs. Also, 10 strikeouts. Henry Urrutia figures to serve as the designated hitter for the last two games of this series. Another right-hander, former Oriole Jeremy Guthrie, starts on Thursday.