Walters, who was placed on the disabled list with right shoulder inflammation on June 14, tossed five scoreless innings against Triple-A Pawtucket, giving up five hits and striking out two.
"He threw the ball pretty decently," Twins manager Ron Gardenhire said. "Had good fastball command but his breaking ball was spotty. His arm felt great. So now we just have to make a decision on the route."
As Gardenhire explained, the Twins can either give Walters one more rehab start with the Red Wings on Thursday or have him rejoin Minnesota's rotation. But the Twins gave no hints as to which way they're leaning yet.
"We haven't decided which way to go," assistant general manager Rob Antony said.