Paulino's ailment was described as a right forearm flexor pronator strain.
"If this was during the regular season, we would miss him a start. He needs to be backed off three or four days to get the tightness and inflammation out of there and get him back," Yost said. "But since we're at a point where we can't afford to do that, we're going to put him on the DL right now, let him get it completely healthy and then go back to pitching. Give him a rehab start or two or three -- whatever it takes -- then we'll see where we are and go from there."
Paulino had been competing with Mendoza and Duffy for the final two spots. In four Cactus League games, Paulino had a 7.71 ERA, giving up 10 runs in 11 2/3 innings.
Tightness in the forearm-elbow area also bothered Paulino during the 2011 season.
"He went through it last year. I think he might have missed a start, but he went through it and finished up the last six weeks of the season real strong," Yost said. "It's just an issue he deals with. He's a real tight-bodied guy."
Mendoza has had a superb Cactus League season with a 0.54 ERA in five starts, giving up just one run in 16 2/3 innings. He also has 16 strikeouts against just three walks and has held opponents to a .180 average.
Duffy, who made 20 starts for the Royals last year, has had a somewhat inconsistent camp with a 7.56 ERA in three Cactus League games. Opponents are hitting .400 against him.
He showed that inconsistency in a Minor League game on Tuesday night against the Texas Rangers' Triple-A lineup. In three innings, he gave up four runs (three earned) on four hits, including a home run. He threw 58 pitches, 36 for strikes.
"His stuff was phenomenal. He lit up the radar gun at 98 [mph]. He was just inconsistent. We've got to work him. He's got ..." Yost said, then paused a moment. "Well, we've always said he's got lightning stuff, electric stuff, great stuff, dynamic stuff, spectacular stuff -- let's go with spectacular today.
"His stuff is spectacular. He's at a stage in his development where he's not the finished product. He's a young player that has spectacular stuff that is still evolving as a Major League pitcher. A guy that's trying to get to where his consistency is constant every time out. Then you can compete."
Yost believes that Duffy is at the point in his career where he needs to develop in the Major Leagues, not the Minors.
The Royals still need to finalize who'll be in the seven-pitcher bullpen. Jonathan Broxton, Greg Holland, Aaron Crow and Jose Mijares are considered locks with six pitchers competing for the remaining three spots. They are Louis Coleman, Tim Collins, Kelvin Herrera, Tommy Hottovy, Jeremy Jeffress and Everett Teaford.
"I look to have the team settled by this weekend," Yost said.
Sanchez will pitch against Minor Leaguers on Thursday, and Mendoza will do the same on Friday. Hochevar will pitch a simulated game on Monday before the Royals leave camp for an exhibition game on Tuesday at San Diego.