Rodriguez (3-10, 6.09 ERA) became the Major League's first 10-game loser after giving up four hits, four walks and six earned runs in three innings in Friday's 9-3 loss to the Rangers.
"There's always concern," Mills said. "When the guys aren't being able to do what we feel they're capable of doing, there's some concern. What we're going to do with Wandy is continue on his program, continue to talk to him about some things, and Arnie's going to work with him on a few things on his side [session] and we might take a different approach for the next outing."
Rodriguez was named the Astros' Pitcher of the Year in 2009 after leading the team and setting career highs in wins (14), games started (33), innings pitched (205 2/3) and strikeouts (193) while posting a 3.02 ERA.