SURPRISE, Ariz. — Camp hasn’t even started, officially, and already the Royals’ low-risk gamble of signing former All-Star reliever George Sherrill shows signs of paying off.

Sherrill threw free and easy Friday in a conditioning workout at the club’s facility and could be ready to return to active duty as soon as late April. That would be less than a year after Tommy John surgery on his left elbow put his career in jeopardy.

The Royals signed Sherrill, who turns 36 in April, to a minor-league deal on Dec. 7. He is a nine-year veteran who was an All-Star in 2008 while saving 31 games for Baltimore.

Seattle signed Sherill as a free agent prior to last season but he made just two appearances before suffering an elbow injury. He is 19-17 with 56 saves and a 3.77 ERA in 442 career games with four clubs.

Just one spot

Newcomer Wade Davis is just as much of a lock for the rotation, manager Ned Yost said, as James Shields, Jeremy Guthrie and Ervin Santana.

“We got him to be a starter,” Yost said. “He’s going to be a starter.”

The only surprise, if any, is the definitive nature of Yost’s comment. The Royals acquired Davis, who spent last season in the bullpen at Tampa Bay, to be a starter in the Dec. 9 deal that also netted Shields for four prospects.

Barring injuries, that leaves just one opening in the rotation with Luke Hochevar, Bruce Chen and possibly Luis Mendoza as the leading candidates.

New bills

Many of the Royals are already sporting the new practice caps, which offer a blue KC logo over a white front panel. It’s a different look.

“I was walking through the clubhouse,” Yost said, “and saw (catcher Julio) Rodriguez with one of them on. I thought he bought it someplace and was about to tell him to take it off.

“But I kept walking, and I’m glad I did. I got to my office, and there was one sitting there for me on my desk.”