Siegrist first felt the tightness after his appearance on May 18. When he next pitched, five days later, he still couldn't get his arm to loosen up as usual. That necessitated further testing, none of which has raised concern about the injury potentially extending to his elbow.
"I'm trying to take precaution with it," Siegrist said. "I threw in the game in Cincinnati, and it wasn't getting better. We decided to take a look at it. It's tight after I release the ball, and it would just stay tight. That's pretty much it."
The Cardinals have prescribed a program of rest and rehab for Siegrist, who will be eligible to come off the DL on June 8.
Jenifer Langosch is a reporter for MLB.com. Read her blog, By Gosh, It's Langosch, and follow her on Twitter @LangoschMLB. This story was not subject to the approval of Major League Baseball or its clubs.