SEATTLE -- The next wave of pitching talent from the Mariners’ pipeline is here, as the club called up top pitching prospect Emerson Hancock to the Majors on Wednesday. The 24-year-old started against the Padres in his big league debut.

As a corresponding move, right-hander Devin Sweet was optioned to Triple-A Tacoma, and to make room on the 40-man roster, left-hander Zach Muckenhirn was designated for assignment.

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To prepare for Hancock's callup, Seattle made four roster moves on Tuesday, headlined with Bryan Woo being placed on the 15-day injured list with right forearm inflammation, retroactive to Aug. 5. The club also recalled reliever Ryder Ryan from Triple-A Tacoma, claimed righty Ryan Jensen off waivers from the Cubs and designated Matt Festa for assignment.

Woo experienced soreness coming out of a bullpen session over the weekend at Angel Stadium, a few days after he threw six strong innings and allowed just two runs on Thursday. Mariners general manager Justin Hollander said Tuesday that there are “no real concerns” with Woo’s situation and that it was more out of “an abundance of caution.”

“We basically took it out of Bryan’s hands,” Hollander said. “If it were purely up to him, he would keep pitching and tough through it. We don’t think that’s a responsible thing to do, so we made an organizational decision.”

Woo, who had an MRI planned for Wednesday, would first be eligible to return on Aug. 20, which in a best-case scenario and with two off-days in this stretch would only force him to miss two starts.

“He's testing strong,” Hollander said. “He has no real symptoms of a significant injury, but he's sore, and we want to be smart. So we don't anticipate, like I said, an IL stint longer, much longer than 15 days.”

Hancock, Seattle’s No. 4 prospect according to MLB Pipeline, joins Bryce Miller and Woo as the third starter called up from Arkansas this season.

Over 98 innings, Hancock has compiled an 11-5 record, a 4.32 ERA and a career-best 26.0% strikeout rate while holding hitters to a slash line of .230/.313/.374 (.687 OPS). He’s been susceptible to runaway starts, with two outings of nine earned runs allowed and another two with six or more. But he’s also registered a quality start in nine of his 20 outings. He’s been particularly good over his past 10 starts, with a 2.97 ERA and 57 strikeouts over 57 2/3 innings.

“He's definitely ready for this,” Hollander said. “This was coming eventually, whether it was this week or next week or the week after.”

As for Miller and Woo, the Mariners had long been preparing for a late-season workload management plan for those two as they reach new career highs in innings pitched -- Woo more specifically, as he’s already reached 99 (including the Minors) after throwing 57 last year.

Miller is at 105 1/3 after reaching 133 2/3 last season. He experienced diminished velocity and inconsistency with his secondary pitches two outings ago before rebounding in a big way on Sunday in Anaheim.

Hancock is at 98 innings and will pass his 2022 total (98 1/3) his next time out. 

"I think Emerson will be fine the rest of the year, but we'll monitor him just like everybody else," Hollander said.

Both Woo and Miller earned their promotions as part of injury replacements to Marco Gonzales and Robbie Ray, respectively. Ray is out for the year due to left flexor and Tommy John surgeries. Gonzales has been sidelined for two months with a left forearm strain, and it’s unclear when he’ll return.

“I think the clock is ticking on that,” Hollander said of Gonzales. “Just the amount of time -- even if he felt great today, he would need a significant ramp up, having been out for a while ... It's becoming less likely by the day.”

That’s left two key rotation spots to fill, which the rookies have done formidably. But there are still many innings to go around for a young group, which have become all the more vital as the Mariners have climbed back into the AL Wild Card race. Now, Hancock will be the latest to help Seattle in its playoff pursuit.