TORONTO -- About two hours before Jack Flaherty was set to make his Orioles debut on Thursday afternoon, the 6-foot-4, 225-pound right-hander walked into the first-base dugout and sat down, looking out toward the field at Rogers Centre while donning red headphones -- he was on the Cardinals only two days before, after all.

Flaherty didn’t say anything to any of the bystanders. Nor did he talk to his new teammates when he walked back into the visitors’ clubhouse to continue preparing for the first of his 119 career big league starts that wouldn’t come in a St. Louis uniform.

Maybe he was just tired after all the prep work that was done Wednesday.

“I had to cut myself off to make sure I, like, slept,” Flaherty said.

Insomnia wasn’t the reason for Flaherty’s stoic gameday presence, though. That’s just who he is -- a 27-year-old who’s laser focused on having success and leading his team to victories.

That’s exactly what Flaherty did as he crafted a masterful performance in Baltimore’s 6-1 series-clinching win over Toronto. He carved up the Blue Jays’ lineup for most of the day, striking out eight over six innings of one-run ball in one of the best pitching debuts in O’s lore.

Flaherty became the first pitcher to go six or more innings with one earned run or fewer allowed in his Orioles debut since Jeremy Hellickson (seven scoreless vs. Royals on Aug. 2, 2017). Flaherty’s eight strikeouts were tied for the fourth most in a Baltimore debut (since 1954) and the most since Bud Norris fanned eight on Aug. 1, 2013, vs. the Astros.

Afterward, Flaherty finally decompressed and delivered messages to both his new squad and the unfamiliar faces of the Baltimore media.

• Flaherty on leaving Cards, joining O's: 'A whirlwind'

“Like I told them in there, I’ll start to actually talk to you guys and learn your guys’ names,” Flaherty said. “The last two days have been kind of just, ‘Go, go, go.’ Now, I look forward to actually building in with these guys.”

The Orioles look forward to having Flaherty around too, especially if this was a taste of what’s to come.

Baltimore needed a boost to its pitching staff, which is why it dealt a trio of prospects to St. Louis in return for Flaherty shortly before Tuesday’s 6 p.m. ET Trade Deadline. The starter had a strong July (3.03 ERA in five starts), and he carried that into his first outing of August.

The bottom of the first began with Whit Merrifield hitting a single and Brandon Belt drawing a walk. Then, Flaherty settled in, escaping that jam and retiring 15 consecutive Blue Jays hitters.

“That was amazing. He shoved,” first baseman Ryan Mountcastle said. “He looked really good and had all of his stuff working.”

Added catcher Adley Rutschman: “He looked phenomenal today. I’m excited to catch him going forward. He brings a great presence to the mound, to the clubhouse, so glad to have him.”

Flaherty ran into some more trouble in the sixth, when Kevin Kiermaier opened the inning with a single and later scored on a Vladimir Guerrero Jr. single that cut the Orioles’ lead to 3-1. Toronto then loaded the bases with one out via a George Springer walk.

Manager Brandon Hyde called to the bullpen to get right-hander Mike Baumann and lefty Danny Coulombe warming. But the skipper stuck with Flaherty in the tough spot.

“He’s been in the league for a while, and honestly, we need our starters to get through the sixth inning, we’re having a tough time,” Hyde said. “Really wanted to see him get through that.”

Flaherty rewarded his new manager’s trust by striking out Matt Chapman and getting Alejandro Kirk to fly out to cap the stellar showing.

Of Flaherty’s 92 pitches, 19 offerings induced whiffs -- including seven of his 12 sliders that were swung at and six of his 10 knuckle-curves that were swung at. He also had great life on his fastball, which touched 97 mph in the first inning for the hardest pitch he’s thrown in any of his 21 starts this season.

Instead of putting pressure on himself to impress a new team -- including a Baltimore front office that had never been Trade Deadline buyers under the present regime (since 2019) -- Flaherty kept his focus on the task at hand.

“You run into a little bit of trouble when you try to do too much instead of just trusting what you do and let the game take care of itself,” Flaherty said. “Go out and throw strikes and keep things really simple.”

With one fantastic start down, Flaherty will look to keep helping the American League-best Orioles (67-42 and a season-high-tying 25 games above .500) push toward their first postseason berth since 2016 and first AL East title since 2014. They continue to thrive in division play, especially against the Blue Jays, improving to 8-2 vs. Toronto this season by taking three of four this week.

One player in the Blue Jays’ lineup knows exactly what the O’s have added to their staff by acquiring Flaherty: Paul DeJong, who was also traded by the Cardinals on Tuesday before going 0-for-2 against his former teammate Thursday.

“Jack, I mean, he works harder than anybody I’ve seen as a starting pitcher. No matter what day it is, he’s in there doing something,” DeJong said. “He really takes pride in what he does.”

The Orioles have now seen that firsthand.