The music was blaring, the P.A. announcer boomed and the Cardinals came out of the locker room like it was their first home game of the season.

But with no fans, Isaiah Simmons admitted "it was kind of weird."

"It's not really what I dreamt of for having my first season, but at the same time, it was still a dream come true to play in the NFL regardless of if there are fans or not." the rookie linebacker said.

It isn't as if Simmons won't have a ton of other concerns when the Cardinals do play a game – without fans – in the season opener Sept. 13 in San Francisco. The first-round pick has been working to find out what his role will be that day and beyond, without an offseason and without preseason games in which to sharpen his skills.

The Cardinals, technically, could bring Simmons along slowly. They have veterans Jordan Hicks and De'Vondre Campbell able to man the two inside spots in the Cardinals' defense. But the Cards didn't take Simmons eighth overall – and by some accounts, a top five talent – without thinking he could make an immediate impact.

"Isaiah has been one of the most impressive rookies I've been around just because of his ability to retain information and understand concepts," Hicks said. "You can tell he was well coached. He's studied football, he understands the concepts of football. All I'm trying to get across is that the speed we're getting right now, you can try to replicate game speed but it's completely impossible.

"Every meeting, every team period, every walkthrough you have to be locked in, because when you get out there on game day, you can't think. You have to go."

Simmons' mental acuity has been long lauded, starting from the man himself. After playing multiple positions in college, Simmons was tested with a heavy intake from the playbook.

"I've kind of been prepped and prepared for this level and how much of a mental strain it'll be," Simmons said.

There are few specifics about what things Simmons will be doing on defense, not a surprise in a training camp in which the Cardinals are trying to keep what they are doing close to the vest. Defensive coordinator Vance Joseph acknowledged Simmons is like many rookies, who can sound sharp in the meeting room and become "just OK" when first testing out plays on the field.

But, Joseph added, "he's a very calm person so when things around him are high (tension), he doesn't waver."

Maybe the best part about Simmons at this point? A mistake might not be devastating on any particular play. Such is the benefit of a 6-foot-4 supreme athlete who acknowledged he can take a false step once in a while and use his physical tools to get back in the play.

"The athleticism can cover up a lot of things," coach Kliff Kingsbury said with a chuckle. "If he's not sure about a coverage or a drop or where he is supposed to be on a certain play, he's so fast, so long and can cover ground so much that he can make up for it. That's been the case at times."

That's OK with Simmons for now. Like Friday's dress rehearsal of player intros, training camp has been about preparations that mean something but don't count just yet.

"You use practice to find out what you can or can't do," Simmons said. "Being able to learn or build off those mistakes in practice is what it is all about -- to learn and make it all come together."

BRICE CARTED OFF

Reserve safety Kentrell Brice was carted off the field after suffering an apparent leg injury during Friday's Red & White Practice. Kingsbury took a moment to say something to Brice on the cart before the veteran was taken to the locker room.

Running back Kenyan Drake did not practice, but he did jog around and was not in the boot he had previously worn.