"It's a completely different mind-set with how I've attacked the game," he said. "I was kind of attacking it from a lower level of the mind. You hear about silence in martial arts. You achieve it and you move and flow better."
Laffey (2-1) scattered eight singles and worked out of trouble in the third and seventh innings. He struck out four and didn't walk a batter.
"I try and take things as stress-free as possible," he said. "I'm the one with the ball and nothing can happen until I throw it."
Laffey said he didn't throw a breaking pitch, used only three changeups and relied on mainly fastballs, changing the grip to make cut fastballs that forced different movements.
"He was using a successful recipe," Blue Jays manager John Farrell said. "There were a lot of strikes, got ahead on the count and got a lot of groundballs."
It was Laffey's second scoreless start against Boston this season. He held the Red Sox to three hits in six innings in Fenway Park on June 26.
The win snapped a three-game losing streak for Toronto, and was just its sixth in its past 15 games.
Boston, which entered the game leading the majors in runs, had won four of five.
Adam Lind added two hits and an RBI for the Blue Jays.
The 27-old Laffey is with the fourth team of his career. He was up with Toronto in April and May but never appeared in a game before being recalled from Triple-A Las Vegas on June 11.
Josh Beckett (5-8) was plagued again by a rough opening inning and took the loss.
"I thought he had good stuff tonight," Boston manager Bobby Valentine said.
Beckett gave up five runs -- four earned -- and seven hits, striking out seven and walking three. Entering Friday's game, the right-hander had a 10.20 ERA in his opening innings and 3.36 combined in all others.
He struck out the first batter, Anthony Gose on a 93 mph fastball. Then Rasmus tripled off the base of the wall in right field and scored when he beat third baseman Will Middlebrooks' throw on Edwin Encarnacion's grounder by slipping his hand ahead of catcher Kelly Shoppach's tag. J.P. Arencibia added an RBI single, making it 2-0.
In the second, Rasmus made it 4-0 with a two-run double into the gap in left-center.
"I thought Will made an aggressive play," Beckett said. "In the second, I needed to make a 3-2 pitch and didn't."
Unlike Thursday, when Boston was held scoreless until pulling out a win in the ninth, there wasn't much drama as the Red Sox scored their only run on Mike Aviles' fielder's choice grounder with one out in the ninth.
Laffey had runners on first and second in the third, but got the next two hitters to fly out. In the seventh, the Red Sox had the first two batters reach with singles.
The Blue Jays made it 5-0 in the fifth on Lind's RBI single and a spattering of boos rained down on Beckett. Encarnacion reached second after Middlebrooks threw his infield hit into Boston's dugout for an error before Lind's hit. Yan Gomes' run-scoring double made it 6-0 in the eighth.
The Blue Jays recalled OF Travis Snider from Triple-A Las Vegas before the game and optioned RHP David Carpenter, acquired in the 10-player trade with Houston earlier Friday, to Triple-A. "For the time being he'll get most of the reps in left," Farrell said of Snider. ... Valentine had a nice pregame line when asked if there was any concern of injuries in walkoff celebrations after the Red Sox beat Chicago in their final at-bat Thursday night. "The more practice you have at celebrations, the better you get at it," he said. ... Red Sox RHP Andrew Bailey, who has not pitched this season as he recovers from right thumb surgery, threw off a mound Friday. Valentine said he may pitch a short batting practice in Texas on Wednesday. ... Farrell said Brandon Lyon and J.A. Happ, acquired from Houston in the trade Friday, should be with the team Saturday.