Few commodities in baseball are as prized as catchers who can handle pitching staffs effectively while providing above-average offense for the position. But because the daily grind—endless squatting, foul balls off the mask, balls in the dirt—takes its toll on knees, noggins and backs, it's easy to understand why teams move offensive stars from behind the plate before they're deep into their declines. It's not exactly a new concept: Joe Torre, Craig Biggio, B.J. Surhoff and Mike Napoli were done with catching by the end of their age 30 seasons. Last fall the Twins decided to protect their remaining $115 million investment in 30-year-old Joe Mauer (left), who has averaged just 114 games since 2011 because of concussion woes and myriad injuries, by shifting him to first base. This spring, the Indians are experimenting with Carlos Santana, 28, at third, where he played before the Dodgers converted him to catching (where his defense has been shaky). The Giants have been mulling a position change for Buster Posey, 27, since he lost most of 2011 to a broken ankle suffered in a home plate collision; third base is an option, which could affect whether they retain pending free agent Pablo Sandoval. The lesson: Everyone wants a catcher who can hit—but hitting too well might be a ticket to another position.