Andre Ellington was surrounded as he came off the practice field Monday, not because of his 57-yard catch or his touchdown in the preseason opener, but because it was announced during practice the Cardinals had agreed to terms with another running back – veteran Chris Johnson.

To this, Ellington smiled.

"As many players as we can get in here to help us win a championship, I'm all for it," he said.

Ellington figures to remain the starter in the backfield, but the addition of Johnson changes the running back dynamic

as the Cards begun their third week of training camp. Johnson, who was with the team Monday and is expected to be on the field Tuesday after signing his one-year deal, is a fast back who can catch – properties coach Bruce Arians has shown he likes most.

To make room on the roster for Johnson, the Cardinals waived-injured safety Brandon Person, who tore his ACL against the Chiefs in Saturday's preseason game. If he clears waivers, he will revert back to the team's injured reserve list.

The possibility of Johnson coming to the Cardinals was a week old, from the time his name first surfaced as a target of General Manager Steve Keim. His arrival would seem to impact most third-round rookie David Johnson, who finally returned to practice Monday on a very limited basis after sitting almost all of camp with a hamstring injury.

Ellington had just returned to practice from a hamstring problem last week, just about the time the Johnson possibility came up. Arians shrugged off the idea the mere thought of the signing motivated either.

"I don't think Andre needed (motivation)," Arians said. "David, he's so young, he probably doesn't even know who Chris Johnson is."

David Johnson, who always seems to be smiling, didn't look any different Monday when asked about Chris Johnson

possibly taking his snaps.

"I can't really feel threatened if I'm not even on the field right now," David Johnson said. "I'm still injured."

Chris Johnson has averaged less than four yards a carry in a season just once, and last year in limited work with the Jets, he averaged 4.3 yards on only 155 rushing attempts. He gained 2,006 yards in 2009 playing for Tennessee and never had less than 1,000 yards for the Titans in his six seasons there.

Johnson also has 296 receptions in his seven-year career, so he can be the receiving option Arians likes out of the backfield if Ellington is not on the field.

Ellington said he studied Johnson's game while in college, and there are similarities between the two. Chris Johnson was shot in the shoulder during an incident in March, but he passed his physical Monday.

Arians said he thought his running backs overall "played pretty solid" against the Chiefs, noting that Kerwynn Williams made a couple of tacklers miss and that Ellington will only get better when he trusts his hamstring to go all out. On the other side, the Cardinals ended up averaging less than three yards a carry.

Now Johnson – once nicknamed "CJ2K" for his big season – arrives to help.

"It gives Coach a lot of options," Ellington said. "The sky is the limit for our offense."