Cardinals running back David Johnson breaks free of the defense on a carry during Arizona's win in Chicago Sunday.

The rookie running back looked very good with limited touches, and even with the talent easy to see – and the fans clamoring for more – Bruce Arians was simply not going to increase the back's workload too far, too fast.

Eventually, in 2013, Andre Ellington was allowed to do more.

David Johnson, the Cardinals' current rookie running back, has been spectacular in his brief and sheltered NFL career. In two games – and with only nine touches – Johnson has three touchdowns, including a franchise-record 108-yard kickoff return and a 55-yard

reception. The small sample size has produced 8.4 yards a carry, and 75.5 yards per kickoff return.

But like Ellington – and Arians acknowledged his handling of Johnson and Ellington is "very similar" – Johnson's role will likely continue to be limited. In 2013, Ellington played behind veteran Rashard Mendenhall. In 2015, Johnson is behind veteran Chris Johnson – and when Ellington returns from his knee injury, he too will jump ahead of the rookie.

None of this is a surprise.

"I definitely talked to Andre a lot about what he did his rookie year," David Johnson said. "He said the same thing: Be patient and it will come to me. B.A. knows exactly what he wants out of the team."

Arians said last week he wants his rookies to earn their playing time. Then someone like David Johnson comes up with multiple explosive plays, and it seems counterintuitive to leave such ability on the bench.

When Ellington was a rookie, he didn't get more than seven carries in a game until the eighth game of the season, and never had more than 12 touches in a game until then.

The reasoning isn't about rookie versus veteran, necessarily. It's a very real concern that too much responsibility would slow Johnson down – especially after Johnson missed a chunk of training camp with a hamstring injury.

"They don't play fast enough, especially in the passing game," Arians said. "We haven't seen him pass protect. He missed all of that stuff in training camp. He's big enough and everything, but until he takes one and gets a little bit better at it … you can only do so much (with him in there) if you can't pass the ball."

Ellington's status remains unknown for this week – Ellington said last week he could still be a week or two from playing – but Arians emphasized Chris Johnson will remain the starter. Chris Johnson leads the team with 109 yards rushing through two games, averaging 3.6 yards a carry. In some ways, Chris Johnson has looked a lot like Mendenhall did in 2013.

David Johnson has had more of an eye-popping start than Ellington, however. By becoming the first player in NFL history to score on a kickoff return, a reception and a rush in his first two games, David Johnson's signed jersey and shoes were shipped to Canton, Ohio Monday to be part of a Hall of Fame exhibit.

"(David) will have a vital role every week," Arians said. "Just how big, we will wait and see."

Johnson can live with that. The patience Ellington preached is part of his personality.

"It's only the beginning of the season," Johnson said. "We haven't gotten that far. I definitely understand where (Arians) is coming from."