Second-year man Elijhaa Penny is in the mix to make the team, and the Cards drafted T.J. Logan in the fifth round. Ellington has been a starter in his career before injuries derailed him.

Williams, meanwhile, has left an imprint.

"Every time we play Kerwynn, he gets 100 yards," Arians said.

Technically, that isn't true, but Williams certainly has performed. In his first NFL start, in 2014, Williams gained 100 yards on 19 carries against Kansas City, and in two other games where he got significant work, he ran for 75 yards (15 carries) and 67 yards (17 carries.) He only had 27 carries all of 2015, but averaged 5.3 yards a carry. David Johnson's emergence last season helped limit Williams to only 18 carries all year, although he averaged 8.7 yards a tote.

"Every time Ker gets an opportunity he makes the most out of it," former Cardinals safety Tony Jefferson, now with the Ravens and one of Williams' close friends, said in a text message. "It always seems when he gets the ball he gains yards. I mean, he was our only 100-yard rusher on the season in '14. He's got a lot of talent he's just been overlooked because of his size ... Proud of that dude. I hope he becomes even more involved as the years progress."

The numbers tell the Cardinals Williams can produce if needed. The numbers also remind Williams that, even as he might move up the depth chart, nothing is promised.