Third baseman Ian Stewart, who received a cortisone shot last week in his left wrist, is not making progress in his rehab.
"The shots and everything don't seem to be making a difference," Cubs manager Dale Sveum said. "I don't know what we'll end up doing with that. There's definitely no progress going on."
Stewart has been sidelined since June 13.
Michael Brenly, son of Cubs television analyst Bob Brenly, hit his third homer and Nelson Perez hit his second in Double-A Tennessee's 13-6 loss to Birmingham on Thursday. Jae-Hoon Ha, who will play in the All-Star Futures Game, had two hits and is batting .253.
Jacob Rogers went 4-for-4 with two home runs in Mesa's 11-2 win over the D-backs in Rookie League action.
Randy Wells, designated for assignment on Wednesday, has cleared waivers and been outrighted to Triple-A Iowa. Wells will join the Iowa Cubs' rotation. Wells was 1-2 with a 5.34 ERA in 12 games with the Cubs, including four starts. As a starter, he was 0-2 with a 7.04 ERA.