The moves cleared roster space for shortstop Yuniesky Betancourt and third baseman Alex Gordon. Both are coming off the disabled list and will be in the starting lineup for Friday night's game against the Tampa Bay Rays.
Pitcher Sidney Ponson reported from his injury rehabilitation assignment but remained on the disabled list with a right elbow strain.
The Royals listed their starting rotation for the Tampa Bay series. Brian Bannister will start the Friday night opener, followed by All-Star Zack Greinke on Saturday night and Luke Hochevar on Sunday.
The club will further evaluate the status of Gil Meche, who left his last start because of a back spasm.
In addition, shortstop Luis Hernandez cleared waivers and accepted an assignment to Triple-A Omaha. He had been designated for assignment by the Royals.
Betancourt and Gordon hooked up with the Royals for a workout late Thursday afternoon and met with reporters.
Betancourt, obtained from the Seattle Mariners last Friday for two Minor League pitchers, had joined Gordon for a few days of rehab with Double-A Northwest Arkansas.
Both players said they were recovered from their injuries -- Gordon from right hip surgery that sidelined him after seven games and Betancourt from a right hamstring strain.
Betancourt told reporters he was feeling "100 percent" on Thursday.
Gordon used the same number but with a qualifier.
"I'm really at 100 percent, it's just kind of that first step getting moving is kind of awkward," Gordon said. "But it's nothing major or anything like that."
General manager Dayton Moore indicated that Gordon would be eased back into full-time action.
"I don't anticipate him being in the lineup more than two or three days in a row at first," Moore said. "We're going to try to use the model of what Alex Rodriguez went through and Mike Lowell went through; they were playing every day with a similar type of injury and we want to go a little slower with Alex. It may be a month or so until we see him running at his accustomed level, or we may not see it until next year."
Gordon was encouraged after being side-by-side with Betancourt for a couple of Texas League games.
"I know I don't have to move a lot to my left because there were a couple of balls in the hole that he got to and made an easy play," Gordon said.
Gordon's return leaves Mark Teahen without an everyday position, but manager Trey Hillman said Teahen would be used to spell Gordon at third as well as play left field, right and possibly some at first base.
Maier's departure leaves center field for Willie Bloomquist, who had been playing shortstop, as well as David DeJesus, who can move over from left field to his old spot.
Zack Greinke, back from his All-Star turn of a perfect inning, was asked about the defense of the "new" left side of the infield.
"I think Teahen and Gordon are about the same defensively, so there won't be much there. And I haven't seen Betancourt play in a while, but I remember when he came up he was supposed to be the best shortstop in all baseball. So I can't see how it changes too much in the last couple years," Greinke said.
Betancourt, his comments translated by coach Eddie Rodriguez, seemed as puzzled as anyone by his .250 average this season.
"He said he prepared well in the offseason for this season, he just doesn't know what things didn't click," Rodriguez said. "He says sometimes players just go through phases like that and he had that this year."
Pena was designated for assignment after 2 1/2 seasons with the Royals. Acquired in March 2007 to replace Angel Berroa, Pena played in 152 games that season and hit better than expected, finishing at .267. He struggled last year and was replaced as the regular in early June by Mike Aviles, who had an outstanding rookie season.
This year, Pena is hitting just .098 (5-for-51) in 40 games. His hallmark, defense, has also suffered this year as he has made five errors in 78 total chances, a .936 percentage.
Maier got his chance in center field after Coco Crisp was knocked out by a left shoulder injury and surgery that ended his season. In 64 games, Maier hit .213 with no homers, three triples, seven doubles and nine RBIs.
An outstanding outfielder, Maier has spent parts of three seasons for the Royals. Last year, he batted .286 and missed 19 late-season games after being hit in the face by a pitch.
Ponson, on the disabled list since June 2, because of a right elbow strain, seemed healthy as he made six starts for Omaha with a 2-1 record and 2.18 ERA.
His future in the starting rotation could depend on Meche's back or if the Royals decide Ponson is a better option to left-hander Bruce Chen, who is 0-4 after four starts.
"He's ready to pitch," Moore said. "He pitched very well in Triple-A, very effective, efficient with his pitches and our reports were very positive."
The Royals don't know if Meche's back is ready.
"The good part of that is that he says his arm feels as good and as healthy as it has all season long. So the arm is not an issue," Hillman said. "It's just a matter of whether we can get the functionality of the back."
Might it be the disabled list for Meche?
"It's not something I like talking about a lot. But it's always a possibility," Hillman said.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.