The solid final month capped his season at 5-10 with a 4.41 ERA in 29 games, with 23 starts. The right-hander logged 143 innings, and he put himself in solid position to claim the fifth-starter spot this Spring Training.
"With September, I felt I showed myself, 'Hey, I can do this.' It was against some quality teams, too," Koehler said.
Koehler's first Grapefruit League start on Tuesday certainly helped his status. In two innings in a 3-1 win over the Twins at Roger Dean Stadium, the right-hander gave up one run on three hits with one strikeout. He threw 36 pitches, 23 for strikes.
A challenging moment came in the second inning, when Koehler loaded the bases with no outs, and he minimized the damage by allowing just one run.
The Marlins maintain they will take the best starting five for their rotation. Even if he doesn't open the season in the rotation, Koehler could make the club as a reliever.
"Come April, I'm going to be pitching somewhere," he said. "I can't tell you where. I hope it's here. For me, the mindset is to go out there and be as ready as I can when the bell rings come April."
A year ago, Koehler got into a pattern of throwing some solid innings, but the outing would be derailed by one rough inning. Eventually, he sat down with manager Mike Redmond to talk about it.
"I had a little meeting with Red, and we talked a little bit," Koehler said. "It kind of helped put some things in perspective and it helped my mindset out. I realized things shouldn't change whether it's the fifth inning of the game or if it's the first inning. Being able to finish strong showed myself -- and hopefully showed them -- that this is a guy who can go out there and help us win games and really compete."
Joe Frisaro is a reporter for MLB.com. He writes a blog, called The Fish Pond. Follow him on Twitter