The Rangers have traded for Nationals shortstop Cristian Guzman, according to a source. Guzman's agent, Stanley King, confirmed the trade. Texas has been looking for help in the infield because it dealt first baseman Justin Smoak to the Mariners in the Cliff Lee deal, then Ian Kinsler went on the disabled list with a strained left groin. The Rangers acquired Jorge Cantu from the Marlins on Thursday.