Cardinals running back Andre Ellington is trying to regain his rookie form.

Andre Ellington was seemingly the odd man out once veteran Chris Johnson re-signed with the Cardinals before training camp, in a running backs room that needed specific skill sets.

Ultimately, though, it was Ellington's attributes – often lost the last couple of seasons as the former rookie sensation battled multiple injuries – that reemerged to make him a player the Cardinals couldn't afford to let go.

Johnson was released as the Cards cut to 53, while Ellington, who signed a one-year deal in March after a brief foray into free agency, remains. What did coach Bruce Arians see from Ellington to make that happen? "I saw Andre,"

Arians said.

"The guy that was there two or three years ago," Arians added. "That run he made in the Hall of Fame game for the touchdown, that was the Andre Ellington of a couple years ago, fighting, spinning, getting it in. And, the dynamic pass receiver that he's been."

If anything were to happen to starter David Johnson, Ellington is best suited to pick up some of the slack in the Cardinals' offense. His receiving ability alone is important; Ellington briefly worked in the wide receivers room in the offseason before moving back to running back.

The injuries have been a problem, and that admittedly caused Ellington frustration.

"Not with my play, because I knew once I got my body in order to where I can play at a high level, it'd be a no-brainer," Ellington said Monday. "But I was frustrated with myself, figuring out my body and some of the things that were happening the way they were, because a lot of the injuries were just freak injuries. I was focused on that. So

far, so good."

Ellington admitted that in the past, especially the season after he was the expected workhorse running back, he trained off-site in the offseason and "didn't come back in the best shape." Arians made clear he wanted Ellington working with Cardinals strength and conditioning coach Buddy Morris.

This offseason he also worked with quarterback Carson Palmer in San Diego, developing on that level.

Arians wasn't just looking at the injuries, however. This offseason the coach noted that Ellington simply needed to run harder. There were times when Ellington looked like he would rather avoid contact, not surprising after various hits had turned into long-term physical breakdowns.

Ellington seemed to take it to heart in training camp and the preseason, showing Arians he indeed could be that dynamic Ellington that was seen in 2013. It earned him a roster spot.

"It was a challenge," Ellington said. "That's just his way of coaching. He put that challenge in front of me and now it's up to me, how bad I want it. Every day I hear that voice when I am on the field. I have something to prove, to keep it going."