The key was Rodriguez finding a brace he was comfortable with.
"He went through a bullpen [session] yesterday with it and felt very good," said Red Sox manager John Farrell. "He had a powerful 'pen yesterday, so I know he's encouraged and just the support that it provides gives him a lot more confidence."
Rodriguez has spent the entire season on the disabled list after suffering a patellar subluxation in his right knee on Feb. 27 while shagging fly balls during batting practice.
"He had a strong work session today with the [pitchers' fielding practice] that he went through," said Farrell. "He felt good coming out of it. He was fitted for a brace. The confidence that he's got from that is substantial. There's evenness to his running gait. He might have favored it a little bit prior, but change of direction, his footwork, all that was very good."
Ian Browne has covered the Red Sox for MLB.com since 2002. Follow him on Twitter @IanMBrowne and Facebook. This story was not subject to the approval of Major League Baseball or its clubs.