"We're going to be careful with the timeline on that. He realizes that too," he continued. "But he looks different to me."
Chalk it up to Rodriguez putting in overtime work last year, when his team was enjoying a second consecutive playoff run. The 29-year-old was seen in the clubhouse almost daily and stayed for most games.
"That was a year well spent, for a guy that had to sit there and watch," Melvin said. "He did it the right way. He studied different pitchers, he knew he was a little bit slow to the plate, and he's already combated that. His mechanics are tighter. He's throwing downhill better.
"And I complimented him on that during the season last year, because he wasn't just doing his rehab and going home. He was staying and watching and learning."
Rodriguez, acquired with Jed Lowrie from Houston last year, is out of options, but will likely remain on the disabled list at season's start so the A's can get him a handful of rehab appearances in Triple-A Sacramento. There's no rush for his return to the big league level, considering Oakland's extensive bullpen depth.
Jane Lee is a reporter for MLB.com. Read her blog, Major Lee-ague, and follow her on Twitter @JaneMLB. This story was not subject to the approval of Major League Baseball or its clubs.