There'll likely be some nerves as well, given Karns will want to make a good first impression on the club that acquired him as part of a five-player swap in November that sent Brad Miller, Logan Morrison and Danny Farquhar to Tampa Bay.
But the former Texas Tech hurler says he's gotten better about being tossed into a new environment, having been traded from the Nationals to the Rays in 2014.
"It's definitely a little easier the second time around," he said. "Bouncing into a new clubhouse and completely new organization, new teammates and staff, the second time around I have a better idea of what I'm getting myself into and the type of work it's going to take to get to know everyone and put names to faces and just kind of be on top of my stuff.
"Because once you're settled in, then you can get comfortable with your surroundings. So far, [Mariners manager Scott] Servais has done a great job with all the new teammates and staff and generating that process for us. He's really opening up that door quicker for everyone."
If everyone stays healthy this spring, Karns figures to challenge James Paxton for the fifth and final rotation berth, but that process is just starting to play out. Servais' early impression of the 6-foot-3, 225-pounder?
"Probably the thing that sticks out to me is he's way more athletic than I anticipated," Servais said. "I really like his demeanor and how he handles himself in the clubhouse and goes about his bullpens and work. He has a very professional approach for a guy who doesn't have that much big league experience yet.
"He's a pretty mature guy and I really like what I've seen so far. We kind of had an idea about his arm and repertoire, but I think he's continuing to develop, even though he had a very nice season last year."
• Nelson Cruz did some running under the watchful eye of trainer Rick Griffin prior to Wednesday's workout as the Mariners look to see how soon he'll be in the lineup after dealing with a sore left knee early in camp. Cruz took batting practice and said he feels good to play, but Servais will leave that decision up to Griffin.
• Servais started most of his regulars in Wednesday's opener, but will now start playing starters every other day for the first week or two of Cactus League play. The infield group of Robinson Cano, Ketel Marte and Kyle Seager will likely start together again Thursday, while the starting outfielders come back in Friday's first road game against the Brewers in Maryvale.
• Left-hander Mike Montgomery returned to camp after having a cyst removed from his neck, but will be held out of practice for a few days. Montgomery said the cyst wasn't a problem, but the medical staff suggested he have it surgically removed after discovering it during his physical exam at the start of camp.
• First baseman/outfielder Efren Navarro signed a Minor League deal and took part in Wednesday's workout after being waived last week by the Orioles. The 29-year-old put up a .246/.303/.324 line in 130 Major League games in four of the past five years with the Angels, including .253 in 83 at-bats last season. Navarro batted .329 with two homers and 29 RBIs in 72 games at Triple-A Salt Lake in 2015.