GLENDALE - The NFL waits for no one, even injured players.
As the Arizona Cardinals begin their second full week of training camp, it's becoming clear head coach Bruce Arians, while disappointed for Ryan Williams, is losing patience with the third-year running back and his inability to stay healthy.
"It's hurting him extremely not to be on the field competing for the job because those other guys are doing so well," Arians said Monday.
Those other guys are rookies Andre Ellington and Stepfan Taylor, plus three-year veteran Alfonso Smith.
Ellington, a sixth-round pick, and Taylor, a fifth-round pick, have yet to separate themselves from one another but they are, according to Arians, "separating themselves from the rest of the pack in that they're playing extremely good, especially on pass protection. They're on their guys. They're aggressive.
"Stepfan is a power back that has really good vision. He likes to run between the tackles. Andre is a slasher who has made some great cuts, in and outside; doesn't have quite the power Stef does," said Arians, describing the two.
"He's a downhill runner. He's bringing it every time, and as our safeties and linebackers have found out, he's a pretty good wall to try to run through on pass protection.
"Alfonso is having a great camp," Arians continued. "I'm excited for Alfonso because I think he's making a really big step in making our football team."
Currently, Ellington, Taylor and Smith are the only healthy running backs on the roster with Williams (right knee) missing his fifth straight practice and Rashard Mendenhall (knee tendonitis) being held out for a third straight practice.
Despite his absence from practice, Mendenhall, whom the Cardinals signed to a one-year contract, would appear to be secure in his position as the No. 1 back given the four seasons he and Arians spent together in Pittsburgh.
Williams may be another matter, however. Each of his first two seasons has ended on the sideline.
"That'll depend on how they all play," Arians answered when asked how many running backs he planned to keep on the 53-man roster. "Probably five. Four or five."
The Cardinals, at the moment, have five running backs on the roster.