New England released Gillislee as a vested veteran, meaning he was not subject to the waiver process and could sign immediately with another team as a free agent.
With Williams gone and Mark Ingram serving a four-game suspension to start the regular season, the Saints were down to two running backs with Alvin Kamara and rookie Boston Scott on the current roster before Gillislee's signing. The Saints also carried two fullbacks with Zach Line and Trey Edmunds, who transitioned from running back during training camp.
The 5-foot-11, 210-pound Gillislee lost a position battle with Jeremy Hill in New England, leading to his release. On his career, Gillislee has played for the Patriots, Miami Dolphins and Buffalo Bills, totaling 1,248 yards and 16 touchdowns on 258 carries, averaging 4.8 yards per attempt.