Mariners keeping prospect in rotation for now following rough debut

Pitching prospect Bryan Woo’s debut with the Mariners didn’t go as either he or the team hoped earlier this week, as the 23-year-old righty was tagged for six runs in two innings by a formidable Rangers offense. However, with Marco Gonzales (flexor strain) and Robbie Ray (Tommy John surgery) sidelined, Woo will remain in the rotation for the time being, general manager Justin Hollander said Tuesday night (Twitter links via Ryan Divish of the Seattle Times and Daniel Kramer of MLB.com).

Woo is one of the more touted prospects in the Mariners system and showed why over the course of the nine Double-A starts that preceded his call to the big leagues. In that time, he pitched to a sterling 2.05 ERA with a 34.3% strikeout rate, a 7% walk rate, a 12.3% swinging-strike rate and just 0.41 homers per nine frames. Though he didn’t storm out of the gates like fellow rookie Bryce Miller, who also made the jump right from Double-A to the majors, Woo will continue to start every fifth day for the time being.

To some extent, that’s largely due to lack of quality alternatives. Ray is done for the season, and while Gonzales’ injury is less severe — Hollander told Divish, Kramer and others that there’s no concern over his ulnar collateral ligament — he won’t be back anytime soon, either. Gonzales likened the injury to one that cost him about five weeks of the 2021 season, per Hollander. If this is indeed similar, he’ll likely be out beyond the 15-day minimum and require a minor league rehab stint before returning late this month or in early July.

Veteran righty Chris Flexen was a key member of Seattle’s rotation for much of the 2021-22 seasons, but he’s struggling through one of the worst seasons of his professional career. Currently pitching in long relief after four rough starts early in the year, Flexen has been rocked for a 7.13 ERA in 35 1/3 frames. His 16.8% strikeout rate is below average but right in line with his 2021-22 levels. However, his walk rate has spiked to 9.3% — his worst as a Mariner — and he’s been rocked for an alarming 2.04 homers per nine innings pitched.

A .351 average on balls in play hasn’t helped Flexen’s cause, and his 20.5% homer-to-flyball rate figures to drop off, given his career 10.8% mark in that regard. Still, his performance of late hasn’t justified another look in the rotation. After beginning his time in the bullpen with eight shout innings, Flexen has yielded runs in three straight outings, yielding a combined seven runs on ten hits (three of them homers) and three walks in his past six frames.

Further depth options for Seattle are also banged up. Right-hander Easton McGee underwent Tommy John surgery last month, and Hollander noted that veteran Tommy Milone and journeyman Jose Rodriguez are both on the minor league injured list at the moment. The same is true of prospect Taylor Dollard, who hasn’t pitched in Triple-A since mid-April. Former first-rounder Emerson Hancock is healthy in Double-A but has been wildly inconsistent this season; he’s sitting on a 5.44 ERA, though nearly all of the damage against him has been done in three starts that have seen him yield nine, seven and six runs. He has a 1.45 ERA in his other eight appearances — including six shutout frames with seven strikeouts last night — but it’s understandable if the Mariners feel Woo’s Double-A consistency makes him the better option at the moment.

As things stand, Seattle’s rotation is still on generally solid ground. Luis Castillo, George Kirby and Logan Gilbert have ranged from good to dominant thus far, and the aforementioned Miller’s career began in historic fashion through five starts before he was clobbered in his sixth and seventh outings. The club can also harbor some optimism that Gonzales will be able to return in relatively short order, though the veteran lefty has had his own struggles with consistency in 2023, leading to a 5.22 ERA in 50 innings.

If there are further injuries and setbacks on the pitching staff, however, that could prove to impact the team’s direction at the trade deadline, which is now fewer than eight weeks away. The Mariners are currently sitting on a 30-30 record, placing them a hefty 10 games back of the first-place Rangers in the AL West but a more manageable five games out of a Wild Card spot. They’ve recently seen key bats like Julio Rodriguez, Ty France and Teoscar Hernandez come to life after extended slumps, but those surges have come in conjunction with alarming swoons from early contributors like Jarred Kelenic, Eugenio Suarez and Cal Raleigh.