The Nationals acquired Ryan Perry from the Tigers for Collin Balester on Friday in a swap of right-handed relievers who split 2011 between the majors and minors. Perry went 5-6 with two saves and a 4.07 ERA in 161 1-3 innings across 149 relief appearances over three seasons with Detroit. Balester was 5-16 with a 5.17 ERA in 62 games -- 40 in relief -- from 2008-11 in Washington.