SEATTLE -- Bryan Woo, the Mariners’ electric right-hander in the midst of one of the best starts to a season in team history, was scratched from his scheduled start on Tuesday due to a right forearm issue that necessitated an MRI.

In his place, veteran left-hander Jhonathan Díaz was recalled from Triple-A Tacoma and started against the White Sox. The Mariners also recalled reliever Eduard Bazardo from Tacoma and designated Mike Bowman and Kirby Snead for assignment, trimming their 40-man roster to 38.

Woo was not placed on the 15-day injured list, and the Mariners are hopeful that he can avoid another IL stint after missing the first six weeks of the season due to right medial elbow inflammation. But there’s nonetheless concern over one of their promising -- and dominant -- young arms.

“It may end up being an IL stint,” Mariners manager Scott Servais said. “And we just give him a couple of weeks down and then see where it goes from there. But those decisions haven't been made yet.”

Servais didn’t want to speculate further until the MRI results are revealed.

“We're always concerned when guys can't make a start,” Servais said. “But he has gone through things like this before and come out just fine with it. So, I know he's a little frustrated. He wants to get out there and pitch. He's off to such a great start. The six starts that he's had this year have just been awesome. So again, I don't want to get ahead of ourselves here. We've just got to wait until we have more information and see where it goes from there.”

Woo alerted the Mariners’ athletic trainers over the weekend that he wasn’t feeling great on the heels of his dominant outing at Oakland last Thursday, and he did not throw a bullpen session between then and Tuesday. The Mariners added Díaz to their taxi squad on Monday in case of need. They made the decision to skip Woo's start and bring up Díaz after Cal Raleigh’s walk-off grand slam later that night.

Servais called Woo’s situation a “similar issue” to the one that’s lingered since he was activated from the IL on May 10.

“It's the same area,” Servais said. “He went through this a couple starts earlier where he didn't [throw] his bullpen and he showed up the day before he had to pitch, he felt better and he went through very, very well that night. That's why [we made] the late decision.”

Woo experienced tightness in his forearm when making his 2024 debut. He also skipped a bullpen session in between his fourth and fifth starts late last month. The Mariners’ athletic trainers and coaching staff have been deliberate about his workload, given the forearm issue and that he nearly doubled his innings total from 2022 to '23 (67 2/3 innings to 131 2/3, including Minors).

Woo underwent Tommy John surgery in the spring of 2021 in college, months before he was selected by the Mariners in the sixth round of that year’s Draft.

He’s topped out at 85 pitches this season, when he blanked the A’s over six innings last week, lowering his ERA to 1.07 -- the best in franchise history among a pitcher’s first six starts. Seattle is also undefeated when Woo has pitched. For the season, Woo has held hitters to a .343 OPS, with only one homer, two walks and 24 strikeouts in 119 plate appearances.

The Mariners opted for Díaz over their other spot-start options -- notably, Emerson Hancock, who filled in for Woo to start the season -- because Díaz last pitched on Wednesday, whereas Hancock last pitched on Friday and hadn’t accumulated regular rest.

Díaz has been Tacoma’s most consistent pitcher, going 7-1 with a 2.98 ERA in 66 2/3 innings across 12 outings (11 starts).