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5/10/2014 2:08 A.M. ET

Crisp misses series opener, gets MRI on neck

OAKLAND -- A's outfielder Coco Crisp was held out of the lineup for Friday's series opener against the Nationals, instead going for an MRI on his strained neck.

Results of the MRI showed "nothing out of the ordinary," manager Bob Melvin said after the game, "so he's literally day to day."

Crisp, who suffered the injury while making a tremendous catch against the center-field wall Wednesday, is not expected to be available Saturday.

In Crisp's stead, Craig Gentry got the start in center field Friday, while John Jaso replaced him in the leadoff spot of the lineup as designated hitter.

Cook heads to DL with right forearm strain

OAKLAND -- The A's placed right-hander Ryan Cook on the disabled list with a forearm strain Friday, and called upon Fernando Rodriguez and Joe Savery from Triple-A for relief help.

The move is retroactive to Wednesday, and the A's will be without Cook for at least two weeks, but they were at least pleased to learn there's no structural damage in the reliever's arm.

"Everything would suggest it's not flexor tendon or ligament, it's more just a strain right in the middle of the forearm," said manager Bob Melvin. "So hopefully that's a good thing. But it's enough to where we felt like we have to DL him."

Cook experienced tightness in his forearm while pitching in the first game of Wednesday's doubleheader against the Mariners, and was removed from the game immediately. He underwent an MRI during Thursday's off-day that revealed the strain.

Rodriguez began the season on the DL while continuing rehab from Tommy John surgery. He has been fantastic since returning to game action for the first time since last March, posting a 0.73 ERA in 11 relief appearances for Sacramento. He did not allow a run over his final 9 1/3 innings.

The right-hander, acquired by the A's with Jed Lowrie from Houston last year, made his Oakland debut Friday night and pitched a scoreless ninth inning in his first Major League game since Oct. 3, 2012, with the Astros.

"Good to see him come all the way back from surgery," said Melvin. "Hard-working kid who really deserves a chance back up here again. We saw him do some good things in Spring Training, and he has been doing well down there, so well-deserved.

"And Joe Savery is another guy that we saw in Spring Training, and that gives you some options, not only against left-handers, but can get some right-handers out, as well."

Savery, who was 4-0 with a 3.86 ERA in 10 relief appearances for the River Cats, allows the A's to keep three lefties in the bullpen, with Drew Pomeranz transferring to the rotation in the wake of Dan Straily's demotion.

The 28-year-old was claimed off waivers by the A's in February, after pitching to a 4.15 ERA in 41 outings spanning three seasons with the Phillies.

Straily sent down, Pomeranz moved into rotation

OAKLAND -- Struggling righty Dan Straily was optioned to Triple-A Sacramento on Friday, leading the A's to name Drew Pomeranz an official member of their rotation following his impressive spot start Wednesday.

Straily had a 2.77 ERA over his first two starts, but a 6.04 mark over his last five while battling decreased velocity and command woes. He issued 15 walks over 38 1/3 innings, and also surrendered nine home runs in that span, tied for the Major League lead.

"He just needs to work on refining his fastball command, getting ahead of guys," said manager Bob Melvin. "We've seen him have success here before, and he just hasn't been as consistent. So we feel like the best avenue for him is to go down and work on things with less pressure than you get at the big league level. Still a guy we expect big things out of."

Straily was consistently reaching 92 mph when called up in 2012. But his fastball velocity has steadily decreased, and he's been averaging 88-89 mph with the pitch. Commanding the pitch, however, has been the bigger issue.

Last week in Boston, Straily threw first-pitch strikes to just three of 20 batters, making his breaking ball ineffective.

"The performance we've seen has gone a little bit backwards," said Melvin.

In contrast, Pomeranz has a history with command issues, but the A's have seen less of that since acquiring him from the Rockies in exchange for Brett Anderson this past winter. The southpaw allowed just three earned runs in 13 2/3 innings for a 1.98 ERA out of Oakland's bullpen before firing five scoreless innings of two-hit ball in the nightcap of Wednesday's doubleheader against the Mariners.

Overall, opponents are hitting .191 against Pomeranz.

"He has pitched his way into this role," said Melvin. "It's difficult to be that long guy, too, when you're not getting regular work. But each and every time we've called on him, he's done a good job for us, and certainly in a starting role, as we saw the day before yesterday."

With Pomeranz removed from the bullpen equation, the A's don't currently employ a true long man, though they have several options to give them at least two innings in Fernando Rodriguez and Joe Savery, called up Friday, as well as Dan Otero.

Worth noting

• Melvin was extremely complimentary of opposing manager Matt Williams in advance of their three-game set in Oakland on Friday.

Williams, in his first year managing, played with Melvin in San Francisco in 1987-88. They also coached together in Arizona.

"He was always a guy that got a lot of respect from his teammates, is all about competition and winning," said Melvin. "He exudes that. We've done quite a few tours together, and a guy that has always had that kind of drive and that winning personality. It was just a matter of time after he got going that he would get a job like this."

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