SEATTLE -- The first time the Red Sox told Darnell McDonald they were going to designate him for assignment was after a game in St. Petersburg against the Rays in May of 2010. But an injury cropped up with Jacoby Ellsbury and the move was never made, allowing McDonald to stay with the team for another 25 months.

The run came to an end Saturday, when McDonald was finally caught in a numbers crunch he couldn't escape. The Red Sox designated for assignment the popular outfielder to create a roster spot for right-hander Josh Beckett, who was activated for his start against the Mariners.

McDonald played in 38 games this season, hitting .214 with two homers and nine RBIs.

In his first game with the Red Sox on April 20, 2010, McDonald became an instant hero, tying the game with a home run and winning it with a walk-off double off the Green Monster.

He had been a journeyman before arriving in Boston, spending the majority of his time in the Minor Leagues.

"Dream come true to play in Boston want to wish my boys good luck the rest of the year! Much love to RSN! #ShowGoesOn," McDonald posted on his Twitter account on Saturday.

After Friday night's win, McDonald showed his selfless nature that made him so beloved in the clubhouse, tweeting, "Cookie pitched a gem! 81 pitches! #CG."

The Red Sox opted to designate McDonald and go with 13 pitchers.

"Oh, really tough," manager Bobby Valentine said of telling McDonald the news. "Darnell is one of those guys that you just love having around. He helped us win some games this year with some big plays defensively and offensively. [He's] one of the guys in the clubhouse that's really well respected."

The Red Sox still have four outfielders on the disabled list in Carl Crawford, Ellsbury, Ryan Sweeney and Scott Podsednik, making it unlikely McDonald could have lasted the season.

"It's a game of numbers and it seemed with all the outfielders who eventually are going to come back, his number was eventually going to be pulled. We decided today would be the day," Valentine said.

Aceves getting restless over lack of work

SEATTLE -- Entering Saturday night's game against the Mariners, closer Alfredo Aceves had pitched just once in the last week, on Tuesday against the Blue Jays.

While some closers might look at that as a much-needed break during the grind of the season, Aceves has great disdain for being out of action.

"Yeah, he loves to pitch, boy, which is a good thing," said manager Bobby Valentine. "I think the more he pitches, the better he is. He was definitely pitching yesterday until we had what we had."

The Red Sox won, 5-0, on Friday, behind an 81-pitch shutout by Aaron Cook.

It's hard for a manager to put a closer into a game just to get him work. Valentine did that earlier this season for Aceves, and it started a string in which he worked for five consecutive games.

Aceves has been one of the underrated stories of the season for the Red Sox. Thrust into the closer's role when Andrew Bailey had right thumb surgery the day before the season began, Aceves struggled mightily in the first couple of weeks.

Since then, he's emerged as a force. Aceves has 18 saves in 21 opportunities.

"I think he gets it," Valentine said. "I think he understands the role. And again, he wants to be sharp when he gets out there, and so do I. I'm very comfortable with him with the ball at the end of the game, absolutely."

In his past 30 games, Aceves is 16 for 17 in save opportunities with a 2.60 ERA and a .203 opponents' batting average.

Ellsbury gets action in center; Crawford belts hit

SEATTLE -- Playing the second game of his Minor League rehab assignment, Jacoby Ellsbury started in center field on Saturday after serving as the designated hitter on Friday.

Ellsbury walked in both of plate appearances and scored a run for the Gulf Coast League Red Sox in Fort Myers, Fla. He played four innings.

Carl Crawford played his fifth GCL game, going 1-for-3 with an infield single. Crawford played five innings in left field.

Ellsbury, who is recovering from a partially dislocated right shoulder, hasn't played for the Red Sox since April 13.

Crawford hasn't played at all in 2012, thanks to left wrist surgery and a sprained UCL in his left elbow.