Holland has four saves this season and has not given up a hit in four scoreless innings. He has been an All-Star the last two years.
"I tried to pitch through it," Holland said. "The ability to recover each and every day as a reliever is important. For me at this point of the season it's smarter for me to go on the DL. I just didn't feel comfortable."
Manager Ned Yost said Holland felt the problem after a save against the Angels on April 11.
"It just didn't feel good and didn't get any better after I was done throwing," Holland said. "I'm pretty optimistic. I feel a lot better today, but I'm a little sore."
The Baltimore Orioles put second baseman Jonathan Schoop on the 15-day DL because of a sprained right knee.
Schoop said he was injured when he tripped over first base in Friday night's game at Boston.
In nine games, Schoop hit .259 with three home runs and seven runs batted in.