GLENDALE, Ariz. -- It was one play among dozens last Monday.

The Arizona Cardinals were in their first day of padded practices during training camp. The first-team offense was facing the first-team defense. Brute strength vs. brute strength. Running back David Johnson, an All-Pro and Pro Bowler last season, split wide as a receiver lining up to the left. First-round pick Haason Reddick, a linebacker, lined up across from Johnson.

As Johnson broke from the line, Reddick dropped back, swung his hips and stayed with him stride-for-stride.

It may have been one play, but that single snap gave the Cardinals a glimpse of the type of player the Cardinals drafted in Reddick and how he, with all his versatility, can impact this season's defense.

"He's probably the best we've ever had as a linebacker being able to cover people," coach Bruce Arians said. "It's just natural ability having been a safety when he was young."

Reddick, whose journey to the NFL took him through three different positions, was a safety in high school and as a freshman at Temple University. When he was given a chance to play for the Owls by their former head coach, Matt Rhule, Reddick was moved to defensive end. At the Senior Bowl in January, he was moved again, this time to inside linebacker, where he will play for the Cardinals, who drafted him 13th overall.

Those years at defensive back set the foundation for an added dimension to Reddick's game that is built on athleticism and confidence.

"First thing, being a competitor -- always being a competitor," Reddick said. "I always feel like I don't want to let anybody beat me. Sometimes that's not the case, but it's always you doing your best."

Reddick's coverage skills quickly caught the attention of one of the best cover men in the NFL.

"He’s very, very fast," cornerback Patrick Peterson said. "He's very instinctive. He's a guy that can guard those middle hashes very well. He can hit, as well. He's a sideline-to-sideline backer. We're definitely happy to have him and can't wait to see what he looks like in game-time situations."

The addition of Reddick gives the Cardinals' defense another dimension, one even beyond safety Tyrann Mathieu.

With Reddick on the field, there’ll be times when Arizona doesn’t need to sub in an extra defensive back. That’ll allow the Cardinals to transition from package to package, scheme to scheme, without having to replace personnel.

"You don't have to substitute," Arians said. "You don't have to substitute at all."

The advantage Reddick has in covering running backs, who either run routes out of the backfield or split wide is his ability to stay with them. Most backs, safety Tyvon Branch said, aren't very good route-runners. That's an issue when he said Reddick is "very good in coverage."

Being able to transition from inside linebacker to covering in space from play-to-play isn't easy, said veteran Cardinals linebacker Karlos Dansby, who is Reddick's mentor. But Reddick has shown signs that he will be able to conquer it relatively quickly at the NFL level.

"It's very hard," Dansby said. "You got to have great technique. You got to trust your technique. If you don't have the speed, you might get left. This game is about angles and leverage. You got to be able to play it at a high level and you got to be able to play it fast."

One of the first times the Cardinals coaching staff saw Reddick drop into coverage was at the Senior Bowl in January. After Reddick was drafted by Arizona, defensive coordinator James Bettcher raved about Reddick's coverage ability. And that was when Reddick was in the beginning stages of transitioning to inside linebacker.

Six months later, Reddick is getting used to his newest role at his newest position.

"I feel really comfortable," he said of dropping into coverage. "I believe in myself. I'm confident in myself. That's No. 1. I got great guys. I got great players around me and they're always helping me out, letting me know if I should be inside leverage, outside leverage, (and) why. It's one thing to tell somebody where to go. It's another thing to tell them why so they can understand."