Knack was optioned to Triple-A Oklahoma City on Thursday, Bill Plunkett of The Orange County Register reports.
Knack will return to Oklahoma City after being called up to the big-league roster Wednesday, collecting a save while tossing 2.2 scoreless innings in the team's 4-2 win over the Royals. The Dodgers selected the contract of right-handed reliever Jonathan Hernandez on Thursday, and Knack was the odd man out with the major-league club.