The Orioles have designated reliever Preston Guilmet for assignment to make room for infielder Alexi Casilla on the 40-man roster. Casilla's contract was purchased today from Triple-A Norfolk and he's starting at third base today.

Casilla, who's wearing No. 1, played 34 games at second base and 21 at shortstop with the Tides. He didn't appear at third base this year. Guilmet, 27, posted a 5.23 ERA in 10 games for the Orioles this season, allowing six earned runs in 10 1/3 innings. He went 4-2 with a 3.91 ERA in 40 games with Norfolk. The Orioles acquired Guilmet from the Indians on April 7 for minor league outfielder Torsten Boss. He didn't allow a run or hit in his first five appearances over six innings, with one walk and eight strikeouts, but he surrendered six runs and eight hits in next five games over 4 1/3 innings. His last outing was July 20. Guilmet was optioned six times this year.