Losing Rackley means undrafted rookie Mike Brewster from Ohio State likely will play a pivotal backup role for Jacksonville this season.
Brewster was one of four undrafted players who made Jacksonville's 53-man roster. Safety Antwon Blake, receiver Kevin Elliott and linebacker Julian Stanford are the others.
The Jaguars released/waived nine veterans: safety Courtney Greene, defensive tackle Corvey Irvin, safety DB Rod Issac, cornerback Trumaine McBride, running back Richard Murphy, quarterback Jordan Palmer, offensive tackle William Robinson, CB Leigh Torrence and WR Demetrius Williams.
They also waived four first-year players: guard Daniel Baldridge, tight end Colin Cloherty, defensive end Odrick Ray and fullback Will Ta'ufo'ou. Ray was waived/injured.
Jacksonville also waived eight rookies: defensive end Kendrick Adams, offensive tackle Lee Barbiasz, receiver Mike Brown, defensive end Ryan Davis, cornerback Antonio Dennard, guard D.J. Hall, linebacker Joshua Jones and linebacker J.K. Schaffer.
The Jaguars can begin signing players to the practice squad Saturday.
With running back Maurice Jones-Drew still holding out in a contract dispute, the Jaguars kept five backs. Rashad Jennings, Montell Owens, Jalen Parmele and Keith Toston made the squad along with fullback Greg Jones.
The Jaguars kept several players who are recovering from injuries, including cornerback Derek Cox, tight end Zach Miller and defensive end Austen Lane.