OAKLAND -- Bryan Woo began the sixth inning on Thursday afternoon at the Coliseum with some rare and visible frustration, quite unseemly given how he’d pitched to that point.

Woo was called for a pitch timer violation by home-plate umpire Nick Mahrley as Oakland’s Abraham Toro stepped into the batter’s box, at which point a confused Woo paced toward the plate to question why. The confab was combative enough to prompt Mariners manager Scott Servais to emerge from the visiting dugout and confer on Woo’s behalf, and for team leader J.P. Crawford to leave his post at shortstop and pull Woo back toward the mound.

For all the commotion and how distracting it seemed, Woo brushed it off. He worked around the 1-0 count to strike out Toro before sitting down Miguel Andujar and JJ Bleday to clear another scoreless inning in an afternoon full of them. Woo’s day was done shortly after, and the Mariners were on their way to a 3-0 win, their ninth in their past 11 games and their sixth behind the second-year starter.

They remain undefeated when Woo pitches, and the statistical superlatives beyond have been remarkable.

Woo’s 1.07 ERA is the lowest in Mariners history for a starter through six outings to open a season. And this year, among 159 pitchers with at least Woo’s season total of 33 2/3 innings, his 0.53 WHIP and .343 OPS against are the Majors’ best, and his ERA is tied for the best. In this stretch, opposing hitters have a slash line of just .139/.160/.183, with only one homer, two walks and 24 strikeouts in 119 plate appearances.

“I think the confidence just comes in the preparation,” Woo said. “It comes in all the stuff that we do throughout the week. It comes in looking at postgame [analysis] and seeing the real stuff -- like I said, counts, where am I batter to batter, inning to inning? Am I falling behind? Am I in good counts or am I in bad counts? How am I setting myself up?

“And then I think doing that stuff consistently and showing that I can do that stuff consistently, that's where the confidence comes from. It's not just like putting up zeros.”

Making the day sweeter was that Woo’s regular crowd of family and friends only had to make the four-mile trek from his childhood home in Alameda, Calif.

Only three baserunners reached against him on Thursday -- Toro with a double to lead off the first inning, Seth Brown on an error by Victor Robles in left field in the second and Tyler Soderstrom with a single in the fifth.

Toro and Brown each wound up reaching third base in their respective sequences, but Woo stranded them there, which proved all the more valuable on a day when the Mariners plated just three runs, starting with a bases-loaded sacrifice fly from Dylan Moore in the third and an RBI single from Mitch Garver to score Cal Raleigh -- who reached scoring position after his second career stolen base -- in the fourth.

Garver then added a critical insurance run in the ninth on a 403-foot solo homer as part of a two-run, two-RBI day. The Mariners are bullish that it could be a sign of good things coming for their top free-agent acquisition.

“They have to. There's no other option,” Garver said. “You cannot continue to hit balls hard right at people through a whole year. It just doesn't happen like that.”

Conversely, Woo has surrendered just four runs this season, none before the fifth inning.

The Mariners’ bullpen -- without Andrés Muñoz, as the closer nurses a lower back strain -- locked down the final nine outs with zero baserunners, via Austin Voth, Mike Baumann and Ryne Stanek.

“Big pitching, awesome job by our bullpen,” Servais said.

Woo tossed a season-high 85 pitches and looked stress-free doing so, with an extra day’s rest this time through the rotation after throwing just 66 pitches in last Friday’s win over the Angels. He threw a light bullpen session in between starts this time around, on Monday’s off-day, something he didn’t do last time.

Woo continues to work through effects from the right medial elbow inflammation that landed him on the injured list just before Opening Day, and the Mariners have been mostly mum on the more detailed symptoms. Yet, a diligent routine has allowed him to pitch through it -- but with a far more watchful eye from the club’s athletic training staff.