Coach Ken Whisenhunt prefers to use multiple running backs rather than rely upon just one to carry the load.
In 2011, however, injuries forced the Cardinals to rely mostly upon Beanie Wells. And he was limited in the second half of the season with a knee injury.
Ideally, Whisenhunt would like to return to an offense that features at least two, and possibly three, running backs. He will be able to do that if Wells has recovered from offseason knee surgery and if Ryan Williams returns after missing his rookie season with a torn patella tendon.
If those two are healthy, they should form a solid duo with contrasting styles.
Wells is a power back. He weighs 230 pounds and can punish defenders, especially once he gets into the secondary.
Williams' strengths are his quickness and vision. He weighs just 207 pounds, but his agility makes him an effective inside runner. At least it should. He has yet to play in an NFL game.
"I think we're both well-rounded running backs," Williams said of himself and Wells. "He's a fast, big guy. His biggest asset is his power. My biggest asset is my quickness and my vision. I really don't have the tangibles. I don't run a 4.2 (40-yard dash).
"But as far as what I can do on the field and what he (Wells) can do on the field, I think we complement each other well."
A year ago, the Cardinals were thin at running back. They traded Tim Hightower at the start of training camp, believing that Williams could be the backup. But Williams' injury left the team thin, and coaches didn't feel confident enough in Chester Taylor or Alfonso Smith to take much of the load off Wells.
Wells had 72 percent of the carries among running backs. Whisenhunt would like more of a 60-40 split. That's what he had as offensive coordinator of the Steelers and in his first four years with the Cardinals.
Problem is, the Cardinals have yet to have Williams and Wells healthy in a real game. Wells missed offseason practices because of his knee, and Williams was limited.
"They've been very cautious with me," said Williams, a second-round pick out of Virginia Tech, "but they should be. Even though it's been nine, 10 months already, my knee isn't quite where it needs to be, and we don't want anything to happen."
If the running backs enjoy good health, Whisenhunt and offensive coordinator Mike Miller think they have plenty of threats. Wells can start and be the power back. Williams will give defenses a completely different look. And LaRod Stephens-Howling has proven he can make big plays on third down and in open-field situations.
Whisenhunt is superstitious, so he's not going to tempt fate by talking about how good his running backs could be.
"When I start telling you about how excited I am," he said, "then something is going to happen."
Arizona's running backs have struggled to be consistent in recent years and must do better in 2012…