ESPN.com's Bill Williamson initially reported the move Monday.
Making the team seemed like an uphill battle for Richardson from the start. Latavius Murray is the incumbent starter, and the Raiders signed Roy Helu Jr. to a two-year, $4.1 million deal this offseason to handle more of the passing-downs duties, a role that could've fallen to Richardson.
Getting cut this early into the process is a bad look for Richardson, and Steve Corkran of RaiderBeat.com believes Oakland's decision is fully justified:
It's hard to believe how far Richardson's stock has fallen ever since the draft.
He looked like a sure thing coming out of Alabama in 2012, having finished third in the Heisman Trophy voting to Robert Griffin III and Andrew Luck. Then Richardson stepped on an NFL field, where he has since been out of his depth.
In three years, he has averaged 3.3 yards a carry with 2,032 rushing yards and 17 touchdowns. When somebody is throwing around the JaMarcus Russell comparison, as ESPN's Damien Woody did, that's a sign things have gone horribly wrong:
It's important to remember Richardson is only 25 years old. While highly improbable, a career renaissance isn't out of the question.
But he'll likely have to wait to get another chance with few teams in desperate need of a running back at the moment. Perhaps Richardson would be better off focusing all of his efforts toward working his way onto a roster next year.