This year, however, circumstances are different, as was Karstens' preparation. In fact, it was a change in circumstances that not only necessitated a change to the right-hander's offseason regimen but have him as determined as ever to prove he can still be an asset.
Karstens had just found out that he was going to be first-year arbitration eligible as a Super Two player when he got a call from general manager Neal Huntington on Nov. 20. Huntington informed Karstens, who appeared in 39 games for the Pirates last season, that he had been removed from the club's 40-man roster.
The Pirates' hope was that Karstens would clear waivers, and he eventually did. That allowed them to invite the righty back to Spring Training as a non-roster player and give him a chance to earn a spot in the bullpen. But don't think that Karstens has forgotten about that phone call.
"It made me say, 'Wow. I have something to prove now,'" he said. "Last year in Spring Training, it was between Virgil [Vasquez] and I for the fifth spot, and neither of us really wanted to take it. So this year I did a lot of preparation to try and make this team."
Karstens worked all offseason with Triple-A Indianapolis strength and conditioning coach Mubarak Malik in Tampa in order to enter spring in better shape. And the dedication has been noticed.
"It's showing," manager John Russell said. "He came to camp more prepared this year physically. He's throwing the ball pretty well."
Karstens still has an uphill battle ahead of him if he wants to be on the Pirates' Opening Day roster. He's no longer in the mix for a spot in the rotation, but the Pirates do have a handful of bullpen spots available for the taking, and Karstens will be among those considered.
Versatility remains Karstens' biggest asset. His ability to pitch in a variety of situations and give the Pirates length can definitely work in his favor when final roster decisions are made. Karstens made 13 starts last and had another 15 relief appearances that lasted more than one inning. All but four of those 15 relief appearances were at least two innings in length.
"Whatever the role is, I just want to help the team win," Karstens said. "I felt like I had some success starting last year. I had some success long relieving. I just want to be as consistent as possible."
However, Karstens isn't the only candidate the Pirates have with the ability to pitch in long relief or spot start. Chris Jakubauskas and D.J. Carrasco have also excelled in similar roles, and Carrasco, particularly, is seen as a favorite to win a bullpen spot. How that affects Karstens' chances is something that will become clearer as Opening Day nears.
Karstens does take some comfort in knowing that he can at least stick to one set of mechanics this spring, something that was far from the case a year ago. Karstens spent much of the spring having his delivery motion altered and continued to tweak it as the season progressed.
But Karstens has arrived here knowing which delivery he wants to run with and is sticking to it. The right-hander worked on it all offseason -- that included making weekly trips to Pirate City in Bradenton -- and is eager to see how it plays in Grapefruit League games.
"When you're trying to learn new mechanics and change your delivery in the big leagues, it's not the easiest thing to do," Karstens said. "These changes that have been made, now let's see where it takes me."
Jenifer Langosch is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.