The Astros are receiving significant interest in star catcher Jason Castro, and once big free agents like Brian McCann and Jarrod Saltalamacchia go off the board, things could possibly intensify.

Castro's name hasn't previously come up as a trade possibility, but the Astros have been known to trade players, even young ones. It isn't certain how serious they are about dealing Castro, who became an All-Star in 2013 for the first time, but Houston is said to like catching prospect Max Stassi very much.

Depending on what happens with the free-agent catchers, the Yankees, Rangers, Red Sox and Blue Jays could have interest. The Angels, Rockies and Twins are other teams that could be looking for a catcher.