Orioles keep finding quality in their rotation

Please remind me again whether the Orioles need to acquire another starter for their rotation or if they should stick with the current five and figure out later how to make room for Ubaldo Jimenez. The rotation has registered a 3.12 ERA in the last 40 games, with Wei-Yin Chen tossing eight scoreless innings last night in a 4-0 victory over the Mariners. If you subscribe to the theory that you don't fix what ain't broke, I know where you stand on this subject. Critics will say the rotation is filled with Nos. 3 and 4 starters and the Orioles won't get deep in the playoffs without a true No. 1. Winning the division may not be an issue, but is this unit capable of delivering a pennant to Baltimore? If someone can figure out a way for the Orioles to obtain that No. 1 without losing Kevin Gausman and Dylan Bundy, you've got their attention. They're not looking to give up their top young arms and they're not interested in swinging a deal for a starter who isn't any better than what they've got. Manager Buck Showalter has made the right call on back-to-back nights by starting David Lough and Delmon Young. He's also on a roll. The Mariners are counting on Felix Hernandez to slow it. Hernandez is 11-2 with a 2.02 ERA in 21 starts this season, with 107 hits, 29 walks and 163 strikeouts in 151 1/3 innings. He's surrendered five home runs. No typos here. These are legit numbers. The Orioles haven't faced Hernandez since 2012, when he had two no-decisions in Mariners losses. He allowed four runs and eight hits in 5 1/3 innings on July 3, and one run and six hits in eight innings on Sept. 19. He walked one and struck out 16 in the two games. Overall, Hernandez is 5-4 with a 3.44 ERA in 15 starts against the Orioles. Nick Markakis isn't impressed. He's 13-for-28 (.464) lifetime against Hernandez. Adam Jones is 8-for-26 (.308) against Hernandez. Chris Davis is 8-for-30 (.267) with two doubles and a home run. Nelson Cruz is 15-for-59 (.254) with three doubles, four homers and 17 strikeouts. Gausman is making his first career appearance against the Mariners. Robinson Cano, the only batter to face him, is 2-for-3. Gausman is 1-1 with a 3.52 ERA in three road starts covering 15 1/3 innings. In his most recent start, Gausman took the loss Sunday in Oakland after allowing five earned runs over four innings to tie his season-high. Darren O'Day tossed a scoreless ninth inning last night to leave his ERA at 1.02, lowest among American League relievers. He hasn't allowed a run in his last 13 appearances over 14 2/3 innings, walking three (two intentional) and striking out 17.