Tazawa has allowed 21 earned runs in 24 career innings against the Blue Jays, which comes out to a 7.88 ERA. Their hitters are 7-for-16 against him this season.
"They're obviously good hitters and I have the history, but I still have to make my pitches," Tazawa said.
Josh Donaldson, Jose Bautista and Edwin Encarnacion each knocked a base hit into left to start off Tazawa's appearance. Chris Colabello then reached on an error by Pablo Sandoval. Finally, Russell Martin delivered the game-breaking blow, a bases-clearing triple that gave Toronto its first lead of the game at 11-8.
Martin's hit, which sailed over Rusney Castillo's head into the center-field triangle, came off a 2-1 splitter.
"I was able to get the first hitter off balance, but that ended up being a hit," Tazawa said. "After that, I think I might have rushed my pitches."
Tazawa entered the game with a 1.33 ERA in 29 games, and his 13 perfect appearances lead all Red Sox relievers. Friday's struggles marked the first time he has given up more than one run in an outing this year.
"Taz is a great pitcher," said Red Sox starter Joe Kelly, who allowed four runs in six innings. "I've never seen that out of him. It's just one of those days where we ran into a team that's swinging the bat very well. They put some good swings on some balls. But I have no doubt he'll come back ready for tomorrow and go do what he usually does."
Alec Shirkey is an associate reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.