“He had a lot of injuries when he was a starter with the Blue Jays, but it looks like he’s found his niche,” Knowles said. “He always threw hard. I wouldn’t have thought he’d be able to go two or three days in a row, but obviously that’s not a problem.”

It had not been a problem when Knowles spoke, just before Game 5. By then, Morrow had thrown more than 12 postseason innings, with a 1.46 earned run average, as the primary setup man for Kenley Jansen.

But Game 5 was Morrow’s 12th outing in the Dodgers’ 13 postseason games, and by the time he was done, an 8-7 Los Angeles lead had become an 11-8 deficit after a homer by George Springer, a single by Bregman, a double by Jose Altuve and another homer by Carlos Correa.

Dave Roberts, the Dodgers’ manager, had said before Game 5 that while Morrow was available, he hoped not to use him. But Clayton Kershaw could not survive the fifth inning, and Roberts deployed Kenta Maeda and Tony Watson to get through the sixth.

He still had four other relievers besides Jansen for the seventh, but Morrow had sent word from the bullpen insisting he was ready.

“When I saw where the game was at in the 7th, I was getting loose and I was feeling O.K.,” Morrow said. “Probably selfish on my part to call down and push to let them know I’m ready and want to get in. They had a plan — we’re obviously very plan-oriented and try to stick to that — and I made them deviate away.”

Roberts called it “a credit to him” that Morrow asked to pitch, and said it would have been hard to turn him down. Morrow, who signed a minor-league contract in January for just $1.125 million, had a 2.06 e.r.a. . — with no home runs allowed — over 45 games this season, averaging more than five and a half strikeouts per walk.