The Rangers believe they bolstered their bullpen and starting rotation Monday by signing reliever Joe Nathan to be the team's closer as Neftali Feliz will make the move into the starting rotation. Nathan, who agreed to a two-year contract worth $14.5M that includes a buyout and a team option for 2014, has been one of baseball's premier closers since 2004 when he joined the Twins, nailing down 35 or more saves in six consecutive seasons through 2009.