Castro, who will turn 34 in March, has played 11 Major League seasons with the Marlins, Mets and White Sox. He is a career .233 hitter with 55 home runs and 186 RBIs.
The South Siders acquired Castro from the Mets last May in exchange for pitcher Lance Broadway, and less than two months later, Castro caught Mark Buehrle's perfect game. It was the first time that Castro had been Buehrle's catcher.
Castro played in 31 games for Chicago in 2009, batting .184 with four home runs and 12 RBIs. But offense isn't necessarily the top priority for the White Sox backup catcher. With A.J. Pierzynski coming off his eighth straight season of catching over 1,000 innings, the White Sox need a backup catcher that can handle a pitching staff. They currently possess one of the deepest pitching staffs in the American League, and Castro already has a good grasp of many of those pitchers.
The move likely means that catching prospect Tyler Flowers will start the year at Triple-A Charlotte. Flowers recently said he was preparing himself for a role with the Major League club but that he was ready for whatever the team had planned for him.
"When I look at the whole offseason, I'm preparing myself to be the starting catcher for the White Sox," said Flowers, during a recent phone interview from his home in Atlanta. "When the White Sox tell me I'm not starting, then I'll prepare to be the backup. And if I'm not the backup, then I'll prepare myself to be back in Charlotte."
To make room on the 40-man roster for Castro, the White Sox designated catcher Cole Armstrong for assignment. Armstrong, 26, batted .252 with 10 home runs and 32 RBIs in 69 games with Charlotte last season.
Kelly Thesier is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.