Ryan Williams' injury puts Cards in bind

The coaching job Ken Whisenhunt and his Arizona Cardinals' staff have done in getting to 4-1 has been admirable.

It just got tougher with news that running back Ryan Williams would under go season-ending shoulder surgery.

This is devastating news for Williams, who had fought back from surgery to repair a torn patella tendon. It's rough news for the Cardinals as well because their depth at running back was already severely depleted.

Arizona went into the 2011 season banking on improved health from its top two running backs. Wells was coming off knee surgery following a 1,000-yard season. Williams was returning from a torn patella tendon. Now, Wells is gone until Nov. 25, when he is eligible to return from a turf-toe injury, and Williams is gone until 2013.

The Cardinals have also been playing without running back LaRod Stephens-Howling, a big-play threat and a player Whisenhunt has worked into the offense beyond the team's no-huddle package. Stephens-Howling is expected back, but he's not a player the team would likely use regularly on early downs.

The challenge for Arizona becomes trying to establish enough of a ground game to avoid becoming too one-dimensional. The team already ranks last in the NFL with a 2.7-yard average per rushing attempt. Relying too heavily on the pass could inflame pass-protection problems surfacing in recent weeks. Kevin Kolb took 17 sacks over the past two games.

William Powell and Alfonso Smith are the other halfbacks on the roster.

Injuries have increasingly become a problem for Arizona this season. The team listed 16 players, including defensive end Darnell Dockett, on a recent injury report.