© 2014 MLB Advanced Media, L.P. All rights reserved.

4/24/2014 9:04 P.M. ET

Griffin to get second opinion on elbow

HOUSTON -- A's right-hander A.J. Griffin, sidelined by a flexor strain for nearly six weeks, will get a second opinion on his pitching elbow in Houston next week.

The A's hoped rest would be the cure for Griffin's ongoing discomfort, which he first felt in the later stages of last season, but it was still there when he attempted to begin a throwing program this week.

"He's throwing a little bit and not feeling much better," manager Bob Melvin said Thursday.

Now there's concern that the issue, once believed to simply be a bout of tendinitis, could lead to surgery.

Griffin will meet with Houston-based Dr. Thomas Mehlhoff on Tuesday to decide if that's necessary. Mehlhoff performed Tommy John surgery on A's reliever Fernando Rodriguez on March 27, 2013, and Rodriguez is nearing the end of what's been a very successful rehab process.

Griffin, 26, was 14-10 with a 3.83 ERA in 32 starts in his first full season in the Majors last year, compiling a team-best 200 innings. But he was left off the American League Division Series roster because of elbow issues, which never went away. They only worsened with each start in Spring Training, and the A's opted to send him for tests with Dr. Doug Freedberg, who suggested Griffin undergo platelet-rich plasma therapy.

Griffin, penciled in as the club's No. 4 starter entering spring, did just that and was initially expected to return to the rotation in late May or early June -- an encouraging prognosis for a team that knew it would already be without righty Jarrod Parker, who succumbed to his second Tommy John surgery in late March.

Suddenly, Griffin could be facing the same fate, though the A's remain equipped with an enviable rotation that entered the day with an AL-best 2.80 ERA.

Johnson working way back into closing mix

HOUSTON -- A's manager Bob Melvin made it clear Thursday that Jim Johnson has not reclaimed the closer's role, but he did suggest the right-hander could be considered part of the ninth-inning mix.

Johnson has strung together several positive outings following an ugly beginning with his new team, and he's increasingly been pitching later in games. The ninth could be next, but only if the situation dictates.

Melvin will still continue to rely on matchups for the ninth inning, meaning Johnson will be considered with fellow righties Luke Gregerson and Dan Otero and southpaw Sean Doolittle.

Johnson has not allowed a run over his last five outings, and opponents are hitting just .200 against him during that stretch. He allowed at least two runs in three of his first five appearances for a 18.90 ERA.

"Nothing's for sure and we're still operating under what we feel are the best matchups, but we've seen him later in games, and there's still potential for that," Melvin said. "He's throwing a lot better than he did earlier in the season, there's no doubt about that. The sinker's down in the zone, he's throwing more strikes, his mechanics look a lot cleaner."

Ryan Cook's outings have also been encouraging, since the right-hander was lifted off the disabled list April 7. But he's still slowly being worked back into high-leverage situations, after missing most of Spring Training with shoulder issues, so he's not considered a current option to close games, Melvin said.

Cook has allowed just two hits in 6 2/3 innings, but he's also walked six.

"He was the one guy coming out of spring late, not as many appearances as the other guys, so we were kind of spoon-feeding him into a more prominent role," Melvin explained. "He just gives us another option late in games, and we have a lot of them."

Moss stands out in A's lineup against lefty

HOUSTON -- Brandon Moss served as the lone left-handed hitter in the A's lineup for their four-game series opener against southpaw Brett Oberholtzer in Houston on Thursday.

That could become a trend, with manager Bob Melvin looking to give Craig Gentry a start each time his club faces a left-hander.

Josh Reddick was the odd man out Thursday, with Gentry getting the nod in right field, suggesting Reddick won't always start against southpaws anymore. He'll seemingly face some, though, as Gentry could play in center field vs. lefties while allowing Coco Crisp to be the designated hitter on occasion.

Moss, meanwhile, got the start over Alberto Callaspo because of "different variables," said Melvin, who didn't provide specifics on how he decides whether Moss should face a lefty, other than noting the style of pitcher often comes into play.

Next time, Melvin said, it could be Callaspo at first base against the lefty. But there's no exact formula, since the right-handed-hitting Nate Freiman -- now at Triple-A, after spending all of 2013 in the Majors -- is no longer an option.

Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.