At this point it's actually quite simple for Arizona Cardinals running back Ryan Williams.

He needs to get on the field and the sooner the better.

A second-round pick of the team's in 2011 Williams has battled injuries pretty much from the get-go. His latest ailment a right knee injury has caused him to miss practices over the last few weeks as well as both of the team's preseason games.

And unfortunately it does not sound like he'll be making his preseason debut when the Cardinals take the field Saturday against the San Diego Chargers at University of Phoenix Stadium.

Williams who has rushed for just 164 yards on 58 career carries has not played enough to show enough and it may cost him a roster spot. The team selected running backs Stepfan Taylor and Andre Ellington in the 2013 NFL Draft to go along with Rashard Mendenhall and Alfonso Smith so it is not as if the team has no depth behind the former Virginia Tech star.

So for Williams being out of action while the team's other four options are on the field making plays is not a good way to impress a new coaching staff.

"He needs to start playing" Cardinals coach Bruce Arians said Monday. "I can't evaluate him unless he plays."

Playing has been an issue that has dogged Williams since his rookie year when a ruptured patella tendon suffered in the preseason opener caused him to miss the entire campaign. Then finally healthy last year he played in just five games before breaking his collarbone Week 5 against the St. Louis Rams.