Lefties Everett Teaford, John Lamb, Will Smith and Chris Dwyer and right-handers Steven Shell and Kevin Pucetas were dropped, reducing the roster to 53 players.
Teaford and Pucetas, who are on the 40-man roster, were optioned to Triple-A Omaha. The other four, all non-roster invitees, were reassigned to Minor League camp.
The moves leave rookies Tim Collins, Danny Duffy, Blaine Hardy and Mike Montgomery as lefties competing for bullpen spots.
2010 Spring Training - null
Sights & Sounds
Spring Training Info
"It's better for them to go over [to Minor League camp] and get their innings, so that when we need them over the course of the year, they're prepared and ready to step back up," Yost said.
Teaford, who blossomed last year with a 14-3 record for Double-A Northwest Arkansas, struggled in Cactus games and gave up 11 runs in 4 1/3 innings. Included in the 14 hits against him were two home runs.
"His stuff was good at times, but his command was an issue," Yost said. "He's a guy that commands the ball, keeps the ball down, changes speeds, works both sides of the plate, and he struggled to do that here."
Lamb, who won the 2010 Paul Splittorff Award as the top pitcher in the Royals' farm system, pitched just one inning this spring, and it was scoreless. Smith gave up four runs in five innings and Dwyer gave up three runs in 3 2/3 innings.
"It was their first Major League experience," Yost said. "They opened up a lot of eyes. We knew what they were, but they were even more impressive to us than we thought they would be.
"But they can't be sitting here and us trying to find innings for them when they've got priority innings over there."
Pucetas, who came from the Giants as the player to be named in the Jose Guillen trade, gave up four runs, including two homers, in four innings. Shell, who had Major League experience with the Nationals, gave up two runs in three innings.
"Instead of having them here backing up every day, we want them over there pitching," Yost said.
Dick Kaegel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.