Phil Simms has a warning for the quarterbacks christened to open their rookie seasons in the starting lineup: Preseason football is not the real thing. A different game looms.

Surely, Caleb Williams, Jayden Daniels and Bo Nix, who sizzled in camps and exhibitions, have heard all about the faster, more complex tests that will come in the regular season.

Soon, they will see this for themselves.

“Better people chasing you. More disciplined people keeping your butt in the pocket. Every aspect of the game is truly different,” Simms, the onetime Super Bowl MVP and longtime analyst, told USA TODAY Sports. “And they’re going to gameplan the hell out of you.”

Maybe that’s why Denver Broncos coach Sean Payton added some colorful perspective as he named Nix the starter on Wednesday.

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“We didn’t have cake and candles,” Payton quipped.

Nix, who beat out Jarrett Stidham and Zach Wilson, was the last of the first-round quarterbacks taken in a record-setting draft marked by the selection of six passers in the first 12 picks. Of all the rookies, Simms maintains that Nix had the toughest trek to the lineup.

“What Sean does with quarterbacks, it’s rough,” said Simms, the former New York Giants quarterback who co-hosts a podcast with his son, Matt, “Simms Complete,” that is distributed on YouTube.

“The calling of the play, all the things that he wants you to do to get to the right play. Do this. Do that. It’s right out of the book with Sean Payton. But the great thing is, it’s right up Bo Nix’s alley. That’s who he is, anyway, the son of a coach.”

Williams, the No. 1 pick overall, had a different path to the lineup for the Chicago Bears. The former USC star was named starter in May before his first rookie minicamp practice. He’s taken all of the first-team reps since then.

There was no suspense, either, with the quick ascension of Daniels to the starting role with the Washington Commanders. The 2023 Heisman Trophy winner, drafted with the second pick, gradually took more of the first-team reps while distancing himself from journeyman Marcus Mariota.

Meanwhile, it’s unclear when Drake Maye, picked No. 3 by the New England Patriots, will surpass veteran Jacoby Brissett and become the starter. Although it seems unlikely that it will happen by Week 1, offensive coordinator Alex Van Pelt wouldn’t rule it out when asked on Thursday.

The comparisons of this crop – which matches the six quarterbacks drafted in the first round in 1983, headed by John Elway – will hardly fade as hindsight and assorted twists and turns will fuel debate.

Will Michael Penix Jr., picked eighth by the Atlanta Falcons, turn out to be the biggest prize? Simms thinks Penix had the best arm in the draft and is bullish on his development. It’s just that barring an emergency, Penix will begin his career on ice as the backup to Kirk Cousins.

And never mind getting another glimpse of Penix before the regular season. Last weekend, Falcons coach Raheem Morris declared that Penix wouldn’t play another preseason snap – a luxury typically afforded to starters. Morris, though, maintained that he has seen enough under those conditions.

“I just wish I knew why they’re not going to play him,” said Simms, who spent the past several years as a studio analyst for "The NFL Today" on CBS. “I keep waiting for something to leak. The general manager (Terry Fontenot), the coach, they’re doing this for a reason. I’m sure it’s going to make sense to them. I’m just a fan right now, going, ‘Damn. Couldn’t I just see some more of it?’ “

The other first-rounder, J.J. McCarthy, drafted 10^th, can’t show anymore until next season. McCarthy was poised to push Sam Darnold for the Minnesota Vikings job until suffering a torn meniscus that wipes out his season.

“Very tough break,” Simms said of the former Michigan standout. “He looks better on the pro field than he did in college. Because they let him go.”

Simms, who has watched every NFL preseason game this month, serves up other impressions of the rookie passers:

• On Williams: “If there’s one detriment, maybe he might rely too much on the fact that I’m just going to make a play, moving around. The last game (vs. Cincinnati), you saw highlight plays. Wow, that was great. But I think those will be far and few between as we get into the regular season…His natural talent is phenomenal. I think he’s going to be a great success. But boy, there’s going to be some growing pains along the way.”
• On Daniels: “He is definitely too cool for school, or whatever they say. He plays the game about as relaxed as anybody I’ve watched in a long, long time. He throws with great rhythm, he runs with rhythm, and all of a sudden, nobody can catch him. His running will impact more than the other quarterbacks. He’s extremely fast, but he does it without effort. And he’s extremely accurate with the football, understanding where to throw it to protect his receivers. What he had in preseason (with ball placement), he can repeat in a regular-season game.”
• On Maye: “I never understand this: They try to manufacture everything so close because they don’t want him to look bad. ‘What if it hurts his confidence?’ Well, if it hurts his damn confidence and it will destroy it that much, he’s not the guy….Let ‘em go out there and screw up. You learn from those things.”
• On Penix: “Against Miami, it was good. I was hoping to see more because of how extraordinary I think he can be. Made a few power throws. He makes them look really easy. I would just like to see more. I’d like to see him move a little more, move around the pocket some more.”
• On McCarthy: “The game in Minnesota (against the Raiders), he was letting go, hitting people down the field, just being more free, running. His speed was real, looking at him on the NFL field. And his arm, it didn’t look good, it looked great. He’s a better power thrower than he is a passer. That’s (Vikings coach) Kevin O’Connell. I don’t know who he really wanted to draft, but he got lucky and found the one that fits him maybe better than the rest of them would’ve fit.”
• On Nix: “Bo looked like he was still playing for Oregon. Everything. In the shotgun, getting rid of the football, making throws on the run, throwing with more power than people give him credit for. Just handling an offense that I would say probably his process to play quarterback for the team is harder than any other rookie in the NFL, for sure.”

The bonus awaits. While Simms doesn’t think Nix will be so fazed by a raucous crowd in Seattle on Week 1, reminiscent of road games at Oregon State or Washington, the Seahawks defense will present a bigger problem. New Seattle coach Mike Macdonald got his shot with the Seahawks because of his ability to design creative defenses for the Baltimore Ravens.

“Strap it up,” Simms warns, “because it’s going to be rough.”

The message is hardly just for Nix. Williams, Daniels and perhaps Maye and Penix can undoubtedly take heed in the theme.

Sure, they’ve had impressive summers. Daniels completed 80% of his passes in the preseason games. Like Nix, he didn’t throw a pick or take a sack. Williams dazzled in throwing on the run and running on the run. Nix produced points on six of his seven preseason drives.

There was a reason six QBs went in the top 12 picks. And the potential has been demonstrated to one degree or another.

“But let’s put in this last little thing,” Simms said. “He did awesome in preseason football.”

And that was hardly the real thing. Maybe those killer preseason showings were just a mirage.