PHOENIX — When Conor Mullee was approached at his locker on Monday, he apologized for not being able to speak with a reporter at the moment. There was a pitchers’ meeting in four minutes, and he could not afford to be late.

“I’m just trying to keep my head down and do my work and figure out how things work here,” Mullee said when he returned about 20 minutes later.

He was not the only player in the Yankees’ clubhouse this month to face a steep learning curve. For all the familiar names there, like C. C. Sabathia, Alex Rodriguez, Mark Teixeira, Jacoby Ellsbury and Carlos Beltran, there has also been a steady stream of little-known players like Mullee, 28, a rookie who overcame three elbow operations before being called up last week from Class AAA Scranton/Wilkes-Barre.

The Yankees have used the last few spots on their 25-man roster to shuffle players to and from Scranton/Wilkes-Barre, not only because of injuries — in addition to Rodriguez, Sabathia and Luis Severino, who are on the disabled list, Ellsbury and Teixeira have missed several games — but also to fill specific needs game to game.