The Broncos had kept Warren on the 53-man roster in hopes he'd return from surgery to repair his torn right triceps by mid-November. But they needed his roster spot to promote running back Jeremiah Johnson from their practice squad with Knowshon Moreno hobbled with a hamstring injury.
Warren was the centerpiece of the Broncos' modest free agency plan, signing a two-year, $8 million deal shortly after his release from the Patriots. He was injured in early August and had surgery a week later.
Johnson is a second-year pro out of Oregon who's been on Denver's practice squad since Dec. 7.