"We've really turned the corner as a team," Arrieta said. "Everybody's just stepping their game up."
Baltimore, which needed 13 tries to finally beat Toronto in Monday's walk-off, turned in its most lopsided victory of the season Tuesday night, sealing its fourth consecutive series 'W' -- three of which were against AL East rivals -- for the first time since Aug. 3-15, 2004.
Tuesday's win also marked Arrieta's first scoreless outing in 18 Major League starts and improved the Orioles to 25-15 under new manager Buck Showalter, whose T-shirt giveaway adorned the backs of the majority of 16,589 on hand at Camden Yards.
"They always say momentum's the pitcher the next day, and I think that's real true," Showalter said of a starting rotation that has continued to toss quality starts, despite several young arms at or above their career high in innings pitched.
"They're starting to feel it a little bit, start to sniff it a little bit," Showalter said. "You can see them kind of look around and go, 'You know what, I can do this.'"
Arrieta, who is 22 2/3 innings above his previous career high (150 2/3), did just that. He pitched around a pair of first-inning singles and allowed just two hits after that to silence the Blue Jays' bats and turn in the O's sixth quality start in seven games.
"Jake's been like that all year," said infielder Robert Andino, who started the season with Arrieta at Triple-A Norfolk. "The only thing is he's getting a little quicker between pitches. He's a solid pitcher. He was keeping us in the game down there, he's keeping us in the game up here. He's giving us a chance to win."
The 24-year-old Arrieta frequently fought his way out of deep counts, striking out five and issuing only one walk, a leadoff free pass to Jose Bautista in the sixth. He proceeded to retire the middle of Toronto's lineup on an infield popup and a pair of ground balls in what would be his final frame.
"For some reason, I think their pitchers are throwing more strikes and getting more people out," Bautista said of a new and improved Oriole squad. "I remember earlier in the year, we walked a lot against them, and got a lot of hits with people on. That certainly hasn't happened in the first two games."
The O's gave Arrieta more than enough offense, with energetic outfielder Felix Pie driving in a run in the fourth and fifth innings and Nick Markakis -- who extended his hitting streak to 10 games with a first-inning single -- clubbing a solo homer. The trio of runs were enough to chase Toronto's starter Shawn Hill from the game after 5 2/3 innings. Hill, who made his season debut on Sept. 9 after spending the majority of 2010 rehabbing back from a second Tommy John surgery, allowed two earned runs on nine hits and a walk before giving way to reliever David Purcey.
Ty Wigginton's leadoff double in the seventh and a one-out walk spelled the end of Purcey's night, although he was charged with a pair of ensuing runs from Adam Jones and Matt Wieters' RBI singles. The Orioles, however, were far from done, plating four runs on Purcey's replacement, Josh Roenicke.
After Roenicke allowed Wieters and Jones to reach safely, Cesar Izturis drew a walk and Josh Bell reached on Roenicke's throwing error, to score another run. Andino, playing in lieu of second baseman Brian Roberts, cleared the bases with a left-field double and Jones belted a two-run shot in the eighth to put the O's in double digits.
"It was just one of those innings where we just exploded," Andino said of the six-run frame, which tied a season high in runs scored in an inning. "We had great momentum, good chemistry."
Tuesday's win improves the Orioles to 49-24 when they score four or more runs and is their eighth win in 13 September games, a month in which they have historically struggled.
"I haven't heard anybody talk about X more days [of the season]," Showalter said. "I think guys are looking forward to coming in and competing, and feeling good about what could be."