He was fourth in the running back chase to replace DeMarco Murray behind Joseph Randle, Darren McFadden and Lance Dunbar. Williams had two arthroscopic surgeries on his left knee in the offseason, the most recent coming after the Cowboys' June minicamp.
Williams spent last year on the Cowboys' practice squad, spurning chances late in the season to join other teams' active rosters. The Cowboys rewarded him with a two-year deal that included a $240,000 signing bonus.
He impressed in the preseason last summer with 25 carries for 112 yards and a touchdown to go along with nine catches for 66 yards, but it was not enough to earn him a spot on the 53-man roster. He was limited in the offseason by the sore knee.
A former second-round pick of the Arizona Cardinals in 2011, Williams' career has yet to take off because of a torn patellar tendon suffered as a rookie. He has not played in a regular-season game since 2012 and averaged just 2.8 yards per carry in the five games he has played.
The Cowboys also released linebacker Cameron Lawrence and offensive lineman Ryan Miller. Lawrence was a special-teams contributor in 2013 and 2014 after making the roster as an undrafted free agent. His spot became tenuous with the additions of Keith Rivers, Andrew Gachkar and Jasper Brinkley in free agency and the drafting of Damien Wilson and Mark Nzeocha.
To fill the three roster spots, the Cowboys signed guard Ronald Patrick, who was with the Cowboys last summer; running back Gus Johnson, who took part in the Cowboys' minicamp on a tryout basis; and linebacker Justin Anderson, who spent time with the New York Giants and Minnesota Vikings last year.