KANSAS CITY -- The Royals, trying to find the right combination for their faltering bullpen, swapped out two relief spots on Friday.

The Royals released Juan Cruz and designated Luis Mendoza for assignment. In their place the Royals brought up right-hander Brad Thompson and left-hander Bruce Chen from Triple-A Omaha.

Both of the new arrivals were starters in the Minors, but will be in the bullpen for manager Trey Hillman.

"I think anybody that's watched us play realizes that if we could've gotten some better performances out of the bullpen, our record could've been flip-flopped and we'd be above .500 instead of below .500," Hillman said.

Collectively the Royals' bullpen went into Friday night's game against Minnesota with a 6.95 ERA, a 3-4 record and five blown saves.

Cruz appeared in five games with a 3.38 ERA and Mendoza was in four games with a 0-1 record and 22.50 ERA. Both are right-handers.

Thompson was 0-1 with a 5.40 ERA in three starts with Omaha. He spent five seasons with the St. Louis Cardinals, going 21-17 with a 4.36 ERA.

Chen also was 0-1 for Omaha but had a 1.31 ERA in three starts. He had 20 strikeouts in 20 2/3 innings. Chen was in 17 games last year for the Royals with 1-6 record and 5.78 ERA.

"Bruce has been throwing the ball very well in the rotation down there," Hillman said. "Thompson got off to a shaky start but he's been throwing the ball better. We'll use both those guys as needed. Having another lefty against the Minnesota Twins never hurts."

The Royals, by releasing Cruz, will be responsible for the rest of his $3.25 million salary for this year as well as the $500,000 buyout on the club option for his 2011 contract. He was signed to a two-year deal in Spring Training 2009 after a brilliant year in relief (4-0, 2.61 ERA, 71 strikeouts in 51 2/3 innings) for the Arizona Diamondbacks.

"It just didn't work out," Royals general manager Dayton Moore said. "We're looking for alternatives to mix and match in the last third of the baseball game. Juan's effort was good, his willingness to do whatever we asked him to do was there but, at the end of the day, we felt it was best to just move on."

Cruz, 31, last year was 3-4 with a 5.72 ERA in 46 games for the Royals. He was on the disabled list with a right shoulder strain from Aug. 6 to Sept. 23.

"I think some days he might not have felt as strong as he'd have liked to," Hillman said. "Some days he didn't feel like he had the strength in his shoulder even though he wasn't hurting. And then he ran into a stretch last year when it was bothering him. It's just one of those things that didn't work out."

Mendoza, if he clears waivers, might be offered a contract by the Royals to be a starter for Omaha.

Chen re-generated his career last year with the Royals after undergoing reconstructive elbow surgery and missing the entire 2008 season.

"My arm feels great, maybe like it did five years ago," he said. "It feels like new."

Both Chen and Thompson were non-roster invitees to Spring Training this year.

"Whenever you have your bosses tell you, 'We're going to keep the ball on the ground and we're going to focus on throwing less pitches,' you know they want movement and to keep the ball down," Chen said.

So that's what he concentrated on all winter and it showed in Spring Training where he pitched primarily in "B" games but was impressive.

"I dedicated myself and have the cutter and the sinker and it's like I have real good command right now," Chen said.

Thompson last year made eight starts for the Cardinals, but was more impressive in his 24 relief outings with a 3.89 ERA so he should feel at home in the bullpen.

"That's great, I've been out of the bullpen most of my career so I'm excited about it," Thompson said. "I have no problem pitching every fifth day, every other day, every single day -- it doesn't matter to me."

Thompson was used immediately, pitching 1 2/3 innings in Friday night's 8-3 loss to the Twins. He gave up a solo home run to Jim Thome.

Just the fact that the Royals chose to eat Cruz's big contract demonstrates, in Hillman's view, a willingness to do whatever is necessary.

"Anytime you make a move, whether it's guaranteed money or not, it says we prefer to win now instead of giving games away because of lack of performance," Hillman said. "We've made three adjustments in our bullpen in the first couple weeks of the season so I think that sends a pretty clear message to everyone."

A week ago the Royals called up right-hander Josh Rupe from Omaha and designated Roman Colon, who cleared waivers and accepted an assignment to Omaha.