BALTIMORE -- With this weekend's roster move -- which added Alberto Castillo in favor of first baseman Rhyne Hughes -- the Orioles are playing with an extra arm over a position player, a situation that will likely remain until the start of Interleague Play on Friday.

"I would think when we'd play a National League club, we'd want another position player for [the] double switch, pinch-hit," manager Dave Trembley said prior to Monday's game. "That's probably, in all likelihood, going to occur."

The Orioles will open up Interleague Play across the beltway in Washington, playing a three-game weekend set at Nationals Park. Prior to that, they have four games -- two each against Kansas City and Texas.

When they do make a roster move, Castillo would be the leading choice to be optioned back. The lefty was recalled from Triple-A Norfolk to give the Orioles bullpen depth, and he allowed a two-run homer in Sunday's loss. Long reliever Mark Hendrickson made Sunday's spot start in lieu of David Hernandez, who is dealing with right shoulder discomfort, which leaves the 'pen temporarily short-handed.

-- Brittany Ghiroli

Hernandez in line to make next start

BALTIMORE -- Orioles right-hander David Hernandez remains on his regular between-starts regimen and is hopeful he will make Friday's start in Washington. Hernandez threw from 90 and 120 feet on Monday without any of the pinching sensation that prevented him from making Sunday's start.

"I was able to get on top of everything and really get in my arm slot," Hernandez said.

He said the discomfort in his right shoulder was "very minimal" during light catch on Sunday, and the big test will be Tuesday's side session.

"I'm assuming if I come through that, I'll make my next start," Hernandez said. "I'm going to be fine."

On Sunday, Orioles manager Dave Trembley expressed equal confidence that the precautionary measure of skipping a start would alleviate the problem. Trembley said the team will have to make a decision concerning Friday's start after Hernandez's side session.

-- Brittany Ghiroli

Uehara could be O's plan B closer

BALTIMORE -- Dave Trembley will continue to use Alfredo Simon as his closer, though the Orioles' manager is intrigued with the notion of running soft-tossing Koji Uehara out to protect a ninth-inning lead because the control-oriented right-hander throws strikes and doesn't waste pitches.

"He's not a strikeout pitcher, he's a flyball pitcher, if you look at his splits," Trembley said. "I don't know if that is your recipe for success if you're a closer,"

Uehara has closed before, and he certainly becomes at least plan B should Simon falter. Simon is 5-for-6 in save opportunities after taking over the role when left-hander Michael Gonzalez and right-hander Jim Johnson were injured.

Since returning from the disabled list on May 6 following a hamstring problem that cropped up in Spring Training, Uehara has been most effective when starting an inning, as opposed to being called upon in the middle of an inning. He has recorded an ERA of 3.00 in four outings covering three innings.

The 35-year-old Uehara, who saved 32 games for the Yomiuri Giants of the Japanese League in 2007, would present a contrast in styles from a hard-throwing setup man. And because Uehara recognizes the importance of pitch efficiency, he could be a closer-in-waiting.

Uehara even broached the subject of closing with pitching coach Rick Kranitz in Spring Training, Trembley said.

"[Uehara] usually gets three outs with a minimum of pitches, so I could see it," Trembley said. "And I think he expressed [interest] to Kranny in spring. But we'll see how it goes."

-- Pete Kerzel