From Chronicle Staff Writer Susan Slusser at Minute Maid Park

Shutting A.J. Griffin down for more than a month does not seem to have resolved the discomfort the A’s starter was feeling. The right-hander will get a second opinion on his elbow from Dr. Thomas Mehlhoff in Houston next Tuesday.

Griffin resumed throwing in the past day or two, manager Bob Melvin said, and things still weren’t feeling right. Griffin has been out with what has been described as flexor tendinitis, which is often a precursor to Tommy John surgery. Griffin first started experiencing some issues late last season.

Mehlhoff did Fernando Rodriguez’s Tommy John surgery last year, and Rodriguez has had about as good a recovery as you could hope for. He was back throwing off a mound a year after his ulnar collateral ligament was replaced and he is currently pitching on a rehab assignment with Triple-A Sacramento and faring well, with a 1.29 ERA in six games. Recovery from Tommy John surgery is typically 12-18 months for a first procedure.

Griffin, 26, was the A’s projected No. 4 starter; he is 21-11 with a 3.60 ERA in 47 starts with Oakland, and the A’s are 31-16 in his starts.

You’d have to think that the A’s were prepared for this eventuality; seldom does a pitcher get shut down for more than a month without needing surgery at some point in the not-too-distant future. So there’s a good chance Oakland has been scouring the trade market for starters (the A’s would do that anyway, of course) but this isn’t the time of year much is available. With Jarrod Parker out for the season and Griffin potentially so, the A’s would definitely be a team looking to add to the rotation at the deadline, even if for just a back-end-of-the-rotation guy. They have very little depth at Triple-A Sacramento; middle reliever Drew Pomeranz might be the next option were the A’s to need a starter, with Josh Lindblom also possible.

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Jim Johnson is pitching better after his early-season issues; he hasn’t allowed a run in his past five appearances, and as Melvin noted, he’s pitching later in games now. Could he be an option in the ninth inning again? Melvin says so, but with an emphasis on could – he’d be part of the mix with Sean Doolittle, Luke Gregerson and Dan Otero. He is not the closer; Melvin will continue to use matchups to determine which man is pitching the ninth.

Ryan Cook is still being worked back in a little on the slow side after missing the start of the spring with shoulder issues. Melvin said that Cook isn’t yet part of the ninth-inning mix, the A’s are “kind of spoon-feeding him into appearances.”

Cook has a 1.35 ERA in seven appearances – but he also has walked six in 6 2/3 innings, which probably is one reason the A’s might be hesitant to have him pitching late in games. That’s second most in the bullpen behind Johnson’s eight, done over 10 innings, and six of those came in Johnson’s first five games.

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Here’s the lineup against lefty Brett Oberholtzer: Crisp CF, Lowrie SS, Donaldson 3B, Cespedes LF, Norris C, Callaspo DH, Gentry RF, Moss 1B, Punto 2B.

It’s becoming apparent that Josh Reddick won’t always start against left-handers any more, with Craig Gentry available. Sometimes, Coco Crisp will DH and Gentry will then play center against lefties, but otherwise, Reddick is probably the odd man out.

Brandon Moss is in against a lefty, and Melvin said next time it might be Alberto Callaspo at first base, but Callaspo is still learning that spot. It’s a juggling act at first base vs. left-handers, now that right-handed hitting Nate Freiman is no longer an option, and Melvin indicated that were are other variables that come into play when choosing a first baseman vs. lefties, including the style of pitcher. Daric Barton doubled and scored the last time the A’s faced Olberholtzer, and Moss did not start and never has faced him.