The team announced Williams' release on Tuesday after the running back underwent another knee procedure in June.
A Cardinals second-round pick in 2011, Williams is a reminder of just how fragile the careers of promising running backs can be.
He was viewed as a future star before rupturing his patellar tendon in his rookie training camp. Unable to stay out of the trainer's room, Williams has managed just 164 yards on 58 carries (2.8 yards per carry) since then.
Despite that lack of production, the Cowboys had high hopes for Williams after signing him to a two-year contract with a $240,000 signing bonus in January.
"His name actually came up quite a bit (during the draft)," executive vice president Stephen Jones revealed in early May. "Many times we were looking at backs later in the draft that we compared to Ryan and didn't feel like they were as good as he was."
Johnson told NFL Media's Rand Getlin on Monday that he is fully healthy, feels more explosive now than he was in 2013 or 2014 and is ready to step in immediately for a new team.
Getlin confirmed that Johnson's agent has been in contact with Dallas, though it's not known if the organization has reciprocated that interest.