MESA, Ariz. -- Manager John McLaren is taking a different approach in selecting a left-handed setup reliever than he used when arranging the numerical order of the starting rotation.

The Mariners camp was barely a week old when McLaren announced his one-through-five rotation. But there remains a mystery as to which lefty in camp will replace George Sherrill as the left-handed bridge to closer J.J. Putz.

"I don't have a time frame," McLaren said on Friday. "It's not something like the starting rotation where we felt we had to address. This is something that's going to work its way through, as we go through Spring Training.

"We've got some guys who know that position is open. You can see the intensity starting to pick up between those guys."

The candidates are Eric O'Flaherty, Cesar Jimenez, Ryan Feierabend and Ryan Rowland-Smith.

They have retired 10 of the 12 left-handed hitters that they've faced, striking out three.

"Right now, they are competing," McLaren said, "but they're really just starting to get their breaking pitches and everything together. We're noticing but they're still working to get in shape.

"When something doesn't go their way, we take into consideration that they've only had one or two appearances. It's more to the end what we're looking for than the beginning."

Sherrill, traded to the Orioles along with outfielder Adam Jones and three Minor League pitchers for left-handed starter Erik Bedard, was rock-solid the past two seasons when used extensively against lefty hitters. He held lefties to a .150 mark (25-for-167).

O'Flaherty, currently being held back because of a stiff lower back, held left-handed batters to a .183 (17-for-93) average last season. Boston's J.D. Drew was the only lefty with an extra-base hit off the Mariners' 23-year-old southpaw.

"I hope so," O'Flaherty said when asked about filling Sherrill's shoes. "That's what I plan to do. I love pitching late in the game."

Jimenez already has pitched himself into the picture.

"The thing I like about him, is that he uses both sides of the plate and he's got a good changeup," McLaren said. "He's somebody who was definitely on the radar screen coming to Spring Training, and he's done nothing but strengthen himself here. I like what I've seen."

One too many: Right-hander Carlos Silva wasn't totally satisfied with the first three innings he pitched on Friday afternoon against the Cubs, so he asked for one more. Maybe he should have stopped at three.

Four of the five batters he faced in the fourth inning reached base and three of them scored in a 6-4 Cactus League loss. Silva was charged with all six runs.

"I felt good, but I was missing my location," he said. "I was all over the place. I wasn't hitting my spots."

Getting greedy: Right fielder Brad Wilkerson got too rambunctious in the seventh inning, trying to stretch a leadoff double into a triple, with the Mariners trailing by two runs. He was thrown out at third.

"You can't get thrown out like that," McLaren said. "There's no excuse for that. He knows he made a mistake, but we need to get that out of our system in Spring Training."

Bruised, not broken: Third baseman Adrian Beltre was held out of workouts on Friday, spending the day getting treatment on his left thumb, which was hit by a ground ball during Thursday's game against the Brewers.

"It's just precautionary," McLaren said. "It caught him in the meat part of his thumb. He iced it. Today, he'll do some cardio work, and [head trainer Rick Griffin] thinks he'll be fine tomorrow."

Beltre, who remained in the game for three innings, said he first injured the thumb last season and it's an ongoing nuisance.

"It will be there all year," he said of the discomfort. "I tried to play through it, but it got a little worse and we decided it was best to have it iced. They don't want me to do anything today, but I should be able to play tomorrow."

Closing the door: With three saves in their first seven games, the Mariners are only four saves shy of last season's Spring Training total. Right-handers Sean Green and Brandon Morrow each have one, and so does Jimenez. The club record for saves in the spring is 10, set in 1998.

Up next: Left-hander Jarrod Washburn, who has been working on a new grip for his changeup this spring, gives it another test on Saturday in his start against the Athletics at Peoria Stadium at 12:05 p.m. PST. By putting more pressure on the middle finger of his hand, the ball breaks down and away to right-handed hitters, rather than cutting back over the plate, which is not a good thing. Right-hander Chris Reitsma, trying to bounce back from his fifth elbow surgery, is scheduled to pitch one inning, as is right-hander Mark Lowe. He also missed much of last season because of injury.