"It's good. It's going to be fun. I enjoyed my time with a lot of those guys in that clubhouse, but to come here and face them, it's just the first time of many, I hope."
Wednesday's game will be the 17th of Karns' career at the Trop. He's started six games at Safeco Field, but no more than three at any other MLB facility. So there is a comfort level, knowing how the stadium plays and facing familiar faces.
But Karns' bigger concern is getting back on track after a pair of rough starts put a wrinkle in what had been an outstanding run to start his Mariners tenure. After going 4-0 with a 2.76 ERA in his previous seven starts, Karns is 0-1 with an 8.64 ERA in his last two outings.
The obvious issue has been 10 walks -- five in each game -- over 8 1/3 innings in two June contests.
"Fastball command has been lacking, and that really showed there in Texas," Karns said of his last outing. "I was making some pitches, they were putting the ball in play, then I kind of crippled myself with walks. Same thing with Cleveland. I felt I was doing really well, then I'd have one or two walks in an inning and put myself in bad situations. So that's what I'm trying to avoid."
Karns still has a healthy 5-2 record and 4.09 ERA in 12 starts after winning the fifth-starter battle in spring. He went 7-5 with a 3.67 ERA in 27 games last year for the Rays in his first full season as a starter before being sent to Seattle in a six-player swap.
"It was a lot of learning," he said, looking back at his time in St. Petersburg. "I was here for two years. I got most of my Major League experience in this stadium, so it's just kind of growing and developing into a Major League starting pitcher. I really kind of came into my own here. My rookie year, establishing who I am and what I can do and really going out and proving it for a full year."
Mariners manager Scott Servais said the key for Karns to return to his early success is to stay more aggressive with hitters when he gets ahead early in counts. If Karns pulls that off, it could be a happy homecoming indeed.
"It's definitely nice to come back and see some former teammates and staff and all that," Karns said. "I got a warm welcome when I came here, and I really appreciate that. But as far as the game goes, I'm anxious to get back out there. I'm trying to get back in the groove of things. I'm ready to come in and compete and help this ballclub any way I can."
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.