Right-hander Grant Varnell had posted a 0-1 record with a 1.64 ERA over eight games with the Wizards before a strained oblique put him on the shelf.
He has held the opposition to a .211 average this year, giving up eight hits in his 11 innings of work while walking two and striking out six.
Stephen Faris, a right-hander out of Clemson, went 2-1 with a 4.65 ERA over 11 appearances, including seven starts, with the Eugene Emeralds last season.
Over 40.2 innings, he allowed 49 hits, walked 10 and struck out 23. The opposition hit .295 off him.