MESA, Ariz. -- Not long ago the A's No. 3 starter, right-hander Jesse Hahn is simply hoping to crack the team's rotation, and he'll seemingly need to put together a near-perfect spring to do so.
A forearm strain prematurely ended Hahn's promising 2015 season, and that was only the beginning of a rocky voyage that has challenged the right-hander both physically and mentally.
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Hahn labored through an ugly Cactus League performance last spring, losing grip of what was supposed to be a secure rotation spot. He spent much of the season with Triple-A Nashville, making just nine starts for the A's before being shut down with a shoulder strain in August.
"I think what happens a lot of times, especially in baseball, is if you have one down year, people forget about you real fast," catcher Stephen Vogt said. "Let's not forget, this guy throws 96, 97 mph with sink, and one of the better curveballs in baseball. I think he could be sneaking up on some people to make this rotation, and no one really talks about him."
Hahn, 27, has already given reason to change that, turning heads in the early going of camp with his signature sinker that's sinking again. After watching Hahn throw a bullpen session this week, A's manager Bob Melvin liked what he saw.
"That really is the difference for him. When his sinker's on, hitters can basically know what's coming and still have a tough time getting it."

Added Vogt: "The ball's coming out real heavy, bowling ball-ish with the sink. My thumb didn't really like it a whole lot."
Hahn's competition for the fifth rotation spot -- up for grabs with Daniel Mengden nursing a surgically repaired right foot -- includes right-handers Andrew Triggs, Frankie Montas and Raul Alcantara. A's front-office members have been touting Triggs all winter. Montas is a promising prospect who has a triple-digit fastball on his resume, and Alcantara is out of options.
Then there's Hahn.
"I think I've flown under the radar my whole career, and I appreciate being the underdog," he said. "That way you control the things you can control, you worry about pitching and getting outs and competing and let all the other stuff fall in place."
Less than two years ago, Hahn threw a four-hit shutout against the Tigers while compiling a tidy 3.35 ERA in 16 starts before a forearm injury and the ensuing woes on and off the mound. In 15 starts for Nashville last year, he had a 4.32 ERA; in nine for Oakland, he posted a 6.02 ERA. Between the two levels, he averaged 4.2 walks per nine innings.
"I think last year I got off to a bad start in spring, and I think it was the first time I ever really struggled in my career," Hahn said. "I don't think I was used to dealing with it. There were times where I was struggling and instead of fixing the problem and working on things I kind of became a little more aggressive and pitched a way I had never pitched before."
Hahn experimented with different arm slots, but to no avail, and he sacrificed movement for velocity, resulting in little life on his fastball. Having rediscovered his natural arm slot, though, Hahn is seeing favorable results, and others are taking notice.
"I think when he's healthy and feeling good," Vogt said, "he's one of the better pitchers we have in the organization."
"With Daniel going down, this is a really good opportunity for Jesse," Melvin said. "When you go through the extremes that he went through the last two years, from basically being our No. 3 pitcher to a guy that bounced around as much as he did, that's tough to deal with, but it'll probably make him a little mentally tougher and up for the challenge this year."