Miller got out of the inning without further damage, but he allowed two more runs in the third and took the loss in the Marlins' 5-2 defeat Thursday.

Miller went 6-10 with a 5.87 ERA with Florida last year. During the offseason he decided the best way to improve was to throw more strikes, so he reworked his mechanics. While the change may ultimately pay off, he has thus far posted miserable numbers this spring.

In his first appearance, Miller yielded six runs in 1 1-3 innings to St. Louis. Against the Orioles, he permitted two earned runs, four hits, hit a batter and issued a walk in 2 1-3 innings - a performance that left him 0-2 with a 14.73 ERA.

"I think in the long run it will make me a much better pitcher," he said of his new delivery. "I've gotten two outings and neither have gone too well for me on the scoreboard, but just getting my feet wet with the new mechanics is good."

Miller might have fared better against the Orioles if not for three Florida errors, including two by second baseman Dan Uggla. Miller faced six batters in the first inning, which ended when right fielder Scott Cousins threw out Luke Scott at the plate to complete a double play.

But in the third, Miller gave up an RBI double to Matt Wieters and was pulled after yielding a run-scoring single to Lou Montanez.

"We've seen him better, and he could be better, but he pitched out of that first-inning jam," Marlins manager Fredi Gonzalez said. "It's a work-in-progress. He just needs a little more consistency."

Miller acknowledged there are times when he thinks too much on the mound because he's not yet comfortable with his more compact delivery.

"It's got a ways to go, but just because it's not second nature doesn't mean I can't be successful," he said.

Uggla, meanwhile, was 1-for-11 with six strikeouts this spring before homering off Jim Johnson in the fourth inning.

Scott and Montanez each drove in two runs for the Orioles, who received three scoreless innings of relief from Brian Matusz, the fourth overall pick in the 2008 amateur draft.

Note: Marlins reliever Scott Proctor will be sidelined at least a few days because of discomfort in his pitching elbow. The right-hander had surgery in October to repair a torn flexor tendon, and the Marlins believe the discomfort is caused by scar tissue breaking up. "We've got to get him back to where you're feeling like you can extend with limited pain and make quality pitches," pitching coach Mark Wiley said. Wiley expects Proctor to be ready when the season starts in April.