MINNEAPOLIS (AP) - Coming off of arthroscopic surgery on his left knee, Joe Mauer tried to take it easy in spring training to conserve his legs for the rigors of catching in the regular season.
Now the Minnesota Twins are saying the All-Star wasn't physically ready to start the season, and will need a rehab assignment in the minor leagues before rejoining the team because of bilateral leg weakness.
"He, I don't think, has had the repetitions either for catching or anything else," head athletic trainer Rick McWane said. "Once the season started, he started to wear down."
McWane said Mauer is feeling better and getting stronger, but has yet to resume baseball activities. Mauer was eligible to come off the DL on Thursday, but there is no timetable for his return.
Mauer had surgery in December and played in only eight spring training games while he tried to ease back into the game.
He started an eight-year, $184 million contract extension this season by hitting .235 with no homers and four RBIs in the first nine games. Then the team put him on the DL April 15 with the leg problems.
"He wasn't strong enough to handle the everyday catching," McWane said. "At the end of spring training, he said it was the best he had felt and he was doing fine. He didn't have any issues with his knee at the end of spring training."
Mauer also lost about a week with a bout of the flu that circulated through the clubhouse. The team initially thought Mauer's soreness may have been partially from the illness, but McWane says that's not the case.
"He had weakness and some soreness throughout his whole body, just from catching," McWane said. "We had discussed that with him and we knew we needed to change some things up to get him stronger. And then, coincidentally, the same day he got sick with a virus."
McWane said he's not sure when the rehab assignment will happen.
Second baseman Tsuyoshi Nishioka, on the disabled list with a broken left leg, will get a follow-up X-ray on Friday. McWane said doctors will decide the next step in his rehabilitation.
"He's getting really close to turning it up a little bit," McWane said. "So, that's why we're getting the X-ray, to see if we can push him through the next step."