Earlier today, John Mozeliak and Mike Matheny held their end of the year press conference, and announced that Yadier Molina needs to have surgery on his thumb.
<blockquote class="twitter-tweet" lang="en"><p lang="en" dir="ltr">Mozeliak: Yadi will be having surgery this afternoon. 8-12 weeks of no baseball activity, but he should be ready by spring training.</p>— St. Louis Cardinals (@Cardinals) <a href="https://twitter.com/Cardinals/status/654708332477870080">October 15, 2015</a></blockquote>
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Molina originally injured his left thumb on September 20th when Anthony Rizzo slid into his glove on a play at the plate. He wound up missing the final 13 games of the season, but was able to make it back for the NLDS against the Cubs.
Unfortunately it was clear that Molina wasn't fully recovered from the injury, as he had difficulty swinging a bat. He started three of the Cardinals four playoff games, but had to be removed after six innings in game three, and didn't play at all in what was their final game of the season.
Molina had a similar surgery in 2014, as he suffered a ligament tear in his right thumb, rather than his left. The Cardinals don't expect this to have any major impact on their All-Star catcher for the 2016 season, and are expecting him to be ready for the start of spring training.