Rolen, who had batted .138 since April 11 and .217 overall with two home runs and 12 RBIs, had been bothered by soreness in his often problematic shoulder lately and had X-rays performed during an exam on Thursday. Team medical director Dr. Tim Kremchek gave him a pair of injections, with hopes that Rolen could return to the field in a couple of days.
In 2005 while with the Cardinals, Rolen missed most of the season with a torn labrum in the same shoulder, which took two surgeries to repair. If there are no issues, he could return to the Reds' lineup when he's eligible for activation on May 6.
"That is certainly the hope," said Rolen, who has shut down trying to hit. "I think it got to the point -- experience has shown -- that this is probably the best move right here. Rest is hard to come by when you're swinging a bat every day. I think that's the answer -- calm it down, rest it and try to get back out there."
With Rolen out, it's likely that Miguel Cairo will get the bulk of the time at third base. Baker didn't rule out using shortstop Paul Janish or Valaika, as well. Ordinarily, the first backup would be Juan Francisco, but he was placed on the DL last Monday because of a strained left calf. Francisco is eligible to return on May 2.
Valaika, who can play three infield positions, has the least amount of experience at third base. He played 11 games this season at second base for Louisville and two games at third base. He played some third base for the Reds during Spring Training.
"It's just reps like any other position," said Valaika, who was batting .306 in 14 games for Louisville. "I moved from shortstop, where I started, to second base and now third -- if that's where the need is. I will get more comfortable the more I do it. I work over there every day and take ground balls, but there's nothing like game speed."
Mark Sheldon is a reporter for MLB.com. Read his blog, Mark My Word, and follow him on Twitter @m_sheldon. This story was not subject to the approval of Major League Baseball or its clubs.