The thumb wasn't the problem. It has been in the papers, on this site and posted by MLB writers on the Twins site ever since Sunday when he was injured. Milwaukee's Weeks collided with Mauer at home plate early in the game. He was kneed in the thigh and continued to play until late in the game. It tightened up and he was removed from the game and has missed playing time because of swelling of the thigh from a deep bruise.
Mauer can hit but couldn't run. So, the pinch hit scenarios have to be well picked. Last night with two on Mauer PH and walk filling the bases. Hendricks (because he pitched the night before pinch ran). There I think you are up to date.
Research may help before you post.
BTW the collision with Weeks was questionable on the part of Weeks. Mauer gave him the plate (though Weeks would have been tagged out regardless), but Weeks actually made a stronger attempt to hit Mauer than go for the plate.