KANSAS CITY, Mo. -- The Los Angeles Angels hope the Jason Grilli they're getting from the Pittsburgh Pirates is the dominant version of last year rather than the struggling one of this year.

The Pirates feel the same way about Ernesto Frieri.

The Angels and Pirates swapped the relievers on Friday night, each team optimistic that a change of scenery will be enough to allow their new arms to revert to their old ways.

"Obviously we're trying to get a bullpen with some chemistry and upgrade it," Angels manager Mike Scioscia said, "and I think Jason Grilli is a guy who can hopefully come in and fill a role, and if he pitches as well as he did last year he could be really important to us."

The 37-year-old Grilli has struggled with his command this season, and was 0-2 with a 4.87 ERA and 11 saves in 22 appearances. But he was pivotal to the Pirates' resurgence last year, when he piled up 33 saves and had a 2.70 ERA in helping the club to a 94-68 record.

"It's a difficult trade to make from the standpoint that Jason had a good run here, and did a lot for our franchise both on and off the field," Pirates general manager Neal Huntington said. "He's loved by a lot of guys in the clubhouse and a lot of fans."

Grilli is expected to join the Angels in Kansas City on Saturday.

"Much like Ernie, he struggled with some things here and there this year after a terrific year last year," Scioscia said. "Once he gets settled and we can evaluate exactly where he is and where his role is going to be to make us as deep as we can be, we'll have a better idea."

Ernesto Frieri has a 7.92 ERA in the ninth inning or later this season. David Richard/USA TODAY Sports

Frieri had a career-best 37 saves for the Angels last year, but the 28-year-old right-hander is just 0-3 with 6.39 ERA and 11 saves in 34 appearances this season.

The final straw may have come the previous night in Los Angeles, when he loaded the bases in the ninth inning against Minnesota. Joe Smith relieved him and gave up a bases-clearing double but bounced back to strike out Kendrys Morales to preserve the 6-4 victory.

Frieri has allowed at least one run in four of his last five appearances, and while he's thrown six shutout frames in the eighth inning, he has a 7.92 ERA in the ninth inning or later.

"Ernesto is a guy we've pursued for a couple of years but haven't been about to get," Huntington said. "He's going through a rough stretch but he's doing things our scouts like and our (statistical) analysts like. We've had success bringing guys in and having them benefit from a change of scenery, a change of league. That's what we're hoping for here."