Tazawa has allowed three of his nine inherited runners to score this month. In his last seven games dating back to Aug. 13, he has a 4.50 ERA and .320 opponents' batting average to go with two blown saves in six innings.
"Throwing-wise I feel very good," Tazawa said Friday night. "It was [six] days since I last pitched. There was a little bit of nervousness going into that inning, but I feel pretty good.
"I understand that there have been some ups and downs. I'm trying my best to limit that up and down, but it hasn't been reflected in the results yet."
Red Sox manager John Farrell pegged a lack of consistent action from Tazawa's splitter as a reason for the recent trouble, but he noted the power and aggressiveness has been there.
"At times, I think he's throwing through his split and not allowing that bottoming-out action to take place," Farrell said.
Ever confident, though, Farrell is sticking by Tazawa, in part because he doesn't have much in the way of other options late in the game.
"It's been inconsistent results, but he's still part of our late-inning mix," Farrell said. "That's who we have down there right now. He's still going to get the ball, and he's going to get the ball in some high-leverage situations."
Tim Healey is a contributor to MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.