Karns -- who was moved to the 'pen last week in part to limit his innings -- allowed a leadoff home run to Detroit slugger J.D. Martinez in the eighth, but he recovered to strike out four without allowing any more damage over three full frames.
"As a starter, you get as much time as you need to get ready," Karns, 27, said Wednesday. "These guys [relievers] need to get ready at the drop of a hat. To really get your arm going in a matter of minutes to a state where you're competitive and you can go right into a game -- that's pretty tough.
"It's like turning on a car in the cold weather and really gunning it."
It's a process Karns may quickly have to grow accustomed to. Tampa Bay manager Kevin Cash plans to use the righty almost exclusively as a long reliever, though Karns may also earn a couple more starts before the regular season ends.
"I think it's very likely, depending on the matchups going forward in those situations, that he'll be back out there in a starting role," Cash said.
Until then, Karns, though, will continue to acclimate himself to the nuances of being a reliever -- most notably, he says, remaining loose throughout the entire game, because the bullpen phone might ring for him at any moment.
"Experiencing it from the other side of the fence, I definitely appreciate what these guys go through," said Karns, who was 7-5 with a 3.69 ERA in 26 starts (144 innings) this season. "It's something new for me, and to see it firsthand and experience it myself was an eye-opening experience."
• Pitching prospect Blake Snell was named USA Today Sports' Minor League Player of the Year, the paper announced Wednesday. The left-hander rose from Class A Advanced Charlotte to Triple-A Durham this year, posting a combined 15-4 record and 1.41 ERA. He's the organization's No. 2 prospect, according to MLBPipeline.com.
• Richie Shaffer made his first career Major League start in left field Wednesday. Cash said the rookie has done extra work in the outfield and that the versatility could help him earn more playing time in the future.