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9/20/2013 9:54 P.M. ET

Freiman continues to sit with abdominal strain

OAKLAND -- For Friday's contest with the visiting Twins, the A's Daric Barton got yet another start against a left-hander over Nate Freiman, who is nursing an abdominal strain.

There's no timetable for his return.

"He's had an abdomen/oblique thing he's been dealing with for about a week and a half, and that's why he's not in there today," manager Bob Melvin explained. "He would've been in there maybe today or tomorrow, but we're not able to get him in there. He hasn't taken batting practice for a few days because of that. We're not sure when we'll get him back."

Freiman sustained the injury while taking swings in the indoor cages, and he hasn't played since Monday. Barton, meanwhile, has seemingly assumed everyday duties at first base, with Brandon Moss spending most of his time in left field while Yoenis Cespedes remains restricted to DH duties for at least a few more days because of a right shoulder injury.

Barton, who is likely to find himself on a potential A's postseason roster, is 18-for-61 (.295) with nine RBIs in 21 games since his return from Triple-A Sacramento.

Melvin confident Cook will snap out of skid

OAKLAND -- Ryan Cook is in a rare funk, and the A's are doing everything they can to help him out of it.

Oakland's chief right-handed setup man was throwing off the mound early Friday afternoon under the close watch of manager Bob Melvin and pitching coach Curt Young, who sorted through video and picked out a couple of mechanical adjustments for the reliever to work on.

Melvin wouldn't go into detail on these but said, "I think over the course of the year, you're always looking to make some adjustments, mechanically, whether you're a hitter, whether you're a pitcher, and you're trying to find out what works well for you.

"You go back and you look at video, and maybe there are some things that have gotten a little bit out of whack. Curt is really good about addressing some of those things, and he was working on some of those things."

Cook allowed two runs on two hits and a walk in one-third of an inning on Thursday night, giving up a lead the A's would ultimately gain back in an 8-6 victory. That brings his total to five runs over his past five appearances, after yielding a total of three earned runs in his previous 29 games.

Even going back a couple of weeks, Cook has allowed 20 hits over his last 12 appearances spanning eight innings. Opponents are hitting .455 (20-for-44) with a .510 on-base percentage during that stretch.

"He went through one of these last year and got through it," said Melvin. "He's a competitor, and it bothers him that he's not contributing how he would like to. He's going to fight his way through it. Everyone goes through it over the course of the season. I can't remember anybody who's been perfect for a whole season. He'll get through it. Sean Doolittle went through a little bit of a tough time, and he got through it. So will Cookie."

Cook's lone rough patch of his 2012 All-Star campaign lasted from July 19 through Aug. 8, spanning eight appearances. In that time, he gave up nine earned runs on 14 hits in nine innings. He proceeded to give up runs in just one other outing the rest of the way.

That's why Melvin believes, "it's only going to take one good outing for him to get back and off to the races again."

"It's not like all of a sudden he's throwing 91 mph. His stuff is good," Melvin said. "If we felt like he was hanging his breaking ball every time, he was getting so far out of whack that his velocity was going down, then we'd have a real issue. I think it's just about him not worrying about some of the stuff that goes on."

Like Thursday, for example. Cook allowed a pair of ground-ball hits, then got an out before unleashing a wild pitch and walking his next batter, leading to his departure.

"Now you start to say, 'OK, here we go again.' Those are the things he's gotta stay away from," Melvin said. "He just got a little frustrated with himself, and that's when you start thinking about what's transpired, and there's nothing you can do about that."

Melvin was undecided on whether he'd attempt to place Cook in a low-pressure situation his next time out.

"We'll see," he said. "I'm not sure yet."

A's open to using Anderson in variety of roles

OAKLAND -- Now knowing that Brett Anderson is in the bullpen for good this season, A's manager Bob Melvin has been able to experiment with the lefty in a variety of roles.

Anderson pitched on consecutive days for the first time in his career this week, getting one out on Wednesday against the Angels before being called on for 1 1/3 innings vs. the Twins. He allowed one run on three hits but also struck out three.

Oakland's southpaw entered this game with two outs and the bases loaded. He offered up an RBI single before putting an end to the frame, all while impressing his manager.

"I think his stuff is better in those type of outings, where he has to go out there and be on it right away," Melvin said Friday. "That's probably the biggest transition for him, going from starting to a reliever. As a starter, you kind of have time to work your way into a rhythm and you get it, whereas a reliever you don't, and I think the times he's been in games where it hasn't been a close game, you've seen some hits and some command issues, whereas yesterday it looked like his stuff was a lot better because he had to be on it right away."

Will Melvin continue to keep Anderson on speed dial in close, late-inning situations?

"Sure," he said. "It depends on the personnel we have available on that day, depends on the matchups, but I think we've moved him around a little bit to where he can pitch in almost every role now, whether it be lengthy or shorter stints like yesterday. Just depends on the variables in a particular day, but, yeah, I'd use him in a close game like we did last night."

Worth noting

• After missing Thursday's game while recovering from a cortisone shot in his ailing right shoulder, Yoenis Cespedes returned to the starting lineup on Friday at designated hitter, where he'll remain for at least a few more days before testing his shoulder in the outfield.

• Former Oakland shortstop Bert "Campy" Campaneris, who started for the 1972, 1973 and 1974 world champion A's, was named to the 2014 induction class of the Latino Baseball Hall of Fame, as announced Friday on MLB Network.

Josh Donaldson enjoyed his 54th multi-hit game of the season on Friday night, which is fourth most in Oakland history. The record is 57, set by Miguel Tejada in 2002 and duplicated by Mark Kotsay in 2004.

Jane Lee is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.