SEATTLE -- Looking to bolster a bullpen that struggled through the first 10 games, the Mariners activated right-hander Tony Zych off the 10-day disabled list on Friday and optioned lefty Dillon Overton to Triple-A Tacoma.
Zych, 26, has pitched just two games for the Mariners since being sidelined a month into the 2016 season with right shoulder issues. He returned to pitch in back-to-back games in late August, but wound up back on the DL and had biceps tendon transfer surgery in October.
Zych adds another power arm to a bullpen that posted a 7.71 ERA thus far and is also awaiting the return of right-handers Steve Cishek (hip surgery) and Shae Simmons (strained elbow), who are still on the disabled list.
Zych, ranked the club's No. 13 prospect by MLBPipeline.com, pitched twice in Tacoma - including one game that was halted by rain - and threw a simulated inning against Mariners hitters before Wednesday's game.
"Tony is healthy," manager Scott Servais said. "He's excited to get back. He looks great. Over the course of rehab and getting back on the mound, he's made a few adjustments that he feels good about mechanically and I do as well. His ability to throw strikes and work his stuff at the bottom of the strike zone will be a nice benefit for us."
Zych had a relatively-rare procedure done by Dr. Stephan O'Brien in New York that eliminated one of his shoulder tendons that was pinching and reattached a longer tendon in a different groove. Zych said he feels better than ever, though he's not sure where his velocity stands yet compared to his former high-90s heat.
"I'm just going off how it feels and it feels great," he said. "The ball is moving late and I think I've got even more life, so I'm excited about it."
Zych has a 2.81 ERA over 32 innings in 25 appearances with Seattle over the past two years, with 45 strikeouts and 13 walks.
Overton made the initial 25-man Opening Day roster, though he spent the season's first three days on the paternity list. He pitched in two games upon his return, giving up three runs in 1 1/3 innings and striking out two.
Overton, rated the Mariners' No. 19 prospect by MLBPipeline.com, will return now to the starting rotation for Tacoma.
Worth noting
• Left-handed reliever Paul Fry, the Mariners' No. 28 prospect, was traded to the Orioles for international signing slot No. 105, which carries a $198,000 bonus. Fry was designated for assignment on Tuesday to open a 40-man roster spot for the addition of utility man Mike Freeman.
• Cishek will begin a Minor League rehab stint early next week and likely need three or four outings before being ready to join the Mariners, according to Servais. He's been sidelined since hip surgery in October.
• Utility man Shawn O'Malley is running and working out at extended Spring Training in Peoria, Ariz., but has not yet begun baseball activities. O'Malley has fully recovered from an appendectomy that he underwent in March, but now is resting a right shoulder that was hampered by tendinitis.