As a career 4-3 linebacker, the former 2006 first-round pick wasn't a good fit for Arizona's 3-4 defense. He didn't materialize into the player Arizona expected when it signed him on June 3, leading to Sims falling on the depth chart.
Cardinals coach Bruce Arians said he released Sims two days before Arizona's first preseason game in order to give Sims a chance to find a new team.
"It was a fit," Arians said. "And I think [as] a veteran you owe him the respect to find a team that he can fit.
"I like where some of the young guys are so I let him go so that he could hopefully catch on real quick somewhere else."
Sims was signed to help build depth at inside linebacker in the wake of Daryl Washington's year-long suspension. The Florida State product was listed on Arizona's depth chart as part of its third unit.
Sims was drafted by Detroit with the ninth pick in 2006 and spent four seasons with the Lions before season-long stints with Philadelphia and Indianapolis. He was signed by Dallas in 2012 to be Sean Lee's backup at linebacker and ended up starting 12 games.