Rookie Greg Mahle, Mike Morin, Jose Alvarez and Fernando Salas were all used in the seventh inning and couldn't hold a 4-2 lead.
In the early part of the season, Scioscia has used matchups to determine the middle-to-late innings in trying to bridge the gap to closer Huston Street, and usual setup man Joe Smith.
"If you're going to match up, you're going to have an occasional inning like that," Scioscia said. "We hoped that inning was going to end with Mike Morin. But it's not going to go as planned every time, and you're going to have an occasional inning like that. We had one tonight."
Scioscia said he considered using Smith in the seventh, but withheld the right-hander because the lead evaporated earlier in the inning.
Mahle, making his second career appearance, replaced starter Garrett Richards with a 4-2 lead to start the seventh and struck out Eduardo Escobar before walking Eddie Rosario. Morin entered and got Kurt Suzuki to pop out, but Eduardo Nunez hit an RBI double down the left-field line.
"Definitely frustrating, it's our job to come in and put the fire out," Morin said. "That whole at-bat [against Nunez], to me, just kind of changed the complexion of the game. I just need to make a better 3-2 pitch. That's what it boils down to. If it's down and away, he's probably not going to be able to do too much with it."
Alvarez allowed an RBI single to Joe Mauer before Salas entered and got Miguel Sano to ground out to end the inning. Salas (0-1) surrendered the go-ahead run on a double by Byung Ho Park in the eighth.
Heading into the game, Angels relievers had held opponents to a .181 average with a 3.34 ERA.
Friday's seventh inning was just an example of Scioscia still trying to clarify his bullpen and its roles.
"I think our bullpen is going to evolve, there's no doubt about that," Scioscia said. "I think we'll get a little bit of clarity as we move on. The best scenario would be for all of them to be throwing the ball well. If they match up, great. If you can get who's ever fresh pitch the seventh inning, that's great too.
"But we're going to do what we need to do to close some games out. I thought we did a great job in Oakland. It didn't happen tonight, but we have a lot of confidence in these guys."