Autographed baseball of Joe Nathan. Joseph Michael Nathan (born November 22, 1974) is an American professional baseball pitcher for the Texas Rangers of Major League Baseball (MLB). Nathan started out his baseball career as a shortstop in high school but converted to a pitcher after being drafted by the San Francisco Giants. He worked his way through the minor leagues, alternating between spots in the rotation and the bullpen. After a few years of splitting time between the majors and the minors, Nathan had a breakout season as a setup man for the Giants in 2003. That off-season, Nathan was traded to the Twins and became their closer.