The Cardinals made a wave of transactions Thursday that will reshape their pitching staff while right-hander Joe Kelly is sidelined with a strained left hamstring.

St. Louis placed Kelly on the 15-day disabled list and optioned right-handed reliever Keith Butler to Triple-A Memphis, and rookie right-handers Eric Fornataro and Jorge Rondon will both be joining the club from Memphis in time for Thursday's series opener against the Nationals in Washington.

Kelly, who pitched to a 1-1 record and a 0.59 ERA in his first three outings, injured his left leg while running to first base during a bunt attempt in Wednesday's game at Milwaukee.

Butler had appeared in two games for St. Louis.

Fornataro and Rondon will both be in the Majors for the first time. Fornataro, a former sixth-round draftee, appeared in four games for Triple-A Memphis this season and did not allow a run. Rondon, who was originally signed by St. Louis out of Venezuela, led Memphis with 51 relief appearances last year.