Andrew Luck isn’t as advertised. He’s better. The rookie quarterback from Stanford has emerged as a physical and emotional leader for the Indianapolis Colts, a team that finished 2-14 last season and looked to be headed for a long winter of rebuilding without Peyton Manning.

Last March, I spent 24 hours with Luck in Tampa, Fla., and got an up-close view of his maturity and humility. ESPN’s Jon Gruden let me join them for Luck’s session at “Gruden’s QB Camp,” that popular program in which the former coach puts the top NFL quarterback prospects through the paces on the white board and the field.

The 24 hours consisted of dinner at a Tampa steakhouse Saturday night, followed by a TV shoot that started early Sunday morning and lasted several hours. Then, we made our way to a local practice field to watch Luck put his passing skills on display.

No one in the NFL — not a coach, personnel executive, or agent — is more familiar with this group of rookie quarterbacks than Gruden, who spent at least one full day with each prospect heading into the draft.

So, now that it’s the midway point of the season, and seeing as a record five rookie quarterbacks were opening-day starters, I called Gruden on Thursday to get his thoughts on the play of those five: Luck, Washington’s Robert Griffin III, Miami’s Ryan Tannehill, Seattle’s Russell Wilson and Cleveland’s Brandon Weeden.

What has impressed you most about Luck?

People have to remember he’s learning a brand-new offense. This is a West Coast offense guru from Stanford. Everything he’s learning he’s doing for the first time. And he’s succeeding arguably the greatest quarterback of our lifetime. The responsibility of being a quarterback and what it takes to replace a legend, that’s asking an awful lot. And to be a first-year player and to play as well as he has, blows my mind.

I can’t say I’m shocked, though. I told you all along, I haven’t met a guy like him. His football aptitude, his upbringing, his physical gifts, he has the rare combination of all of it. If he stays healthy and they continue to get better around him, he’s one of the few guys I would ever say that could be as good or better than Peyton Manning.

What didn’t you know about him back in March that has surfaced now?

I didn’t know how good the supporting cast was. I didn’t know a whole lot about some of their players, how well he’d take to a new offense. But obviously he’s got some pretty good players around him, and Bruce Arians, this isn’t his first rodeo. [Interim Coach] Bruce Arians called the plays for a championship team, so you’ve got to give him some credit also.

Griffin has been really effective at times and has struggled at others. Where is he in his development?

The offense they’re running in Washington is one that no one had seen before this season. It’s an offense that you have to see and really take some time to prepare for. It’s hard to emulate the speed that Robert Griffin plays with. So that’s the double-edged sword: You’re dealing with an offense that you’ve never seen before, and a quarterback that can really run.

I think 3-4 defensive teams are better equipped for handling the edges. Once you’re studying the Redskins and you’ve seen them four or five times, you have a better opportunity to draw some plays up on a card and prepare for them.

If the novelty of that offense is an advantage, what happens when opponents get used to it?

That’s Mike Shanahan. In his back pocket he’s holding the keys to the adjustments. I just have to believe that in the development of Robert Griffin, he’s not only going to be able to do what he’s doing now, but he’s going to be able to do the things that Mike did with John Elway and Steve Young along the way.

The Seahawks are 4-0 at home with Wilson, and 1-4 on the road. His passer rating reflects that. What’s going on there?

The league is set up for a lot of 8-8 teams. There’s a lot of things Russell can do better and needs to do better. The more he plays, and the more Seattle puts around him, the better he’ll be.

What are your impressions of him overall?

From day one he went in there and moved the team, put points on the board, and won over the locker room. That’s a great accomplishment. Here’s a guy playing with a very young offensive line, a very inexperienced receiving corps — other than Sidney Rice, who’s had injuries — and he beat Tom Brady. I’m not saying he did it alone, but he brought them back to beat Tom Brady. Look at the quarterbacks he’s gone up against and beaten. It will show you what kind of stuff he has.

How important is it that Tannehill has offensive coordinator Mike Sherman with the Dolphins, the guy who was his head coach at Texas A&M;?

I credit system familiarity — not only the system, but the coach, who knows what his strengths and weaknesses are, and has helped fast-track him. He can handle a lot of football. This kid’s a sponge for the game. You can call no-back sets, two-back sets, check-with-me’s, this guy’s been very well-trained at a young age at Texas A&M;, and it shows right now. He’s further along than a lot of young guys that have come into the league.

Weeden is the guy in this group who has had the bumpiest transition. How do you assess him?

Tough place to play quarterback, right on that lake. It’s cold, it’s wet. They have some young linemen playing, an obscure group of receivers. Cleveland Browns have been in games. The thing Weeden has really shown me is how tough he is. He’s taken some real licks. He’s hung in there and brought his team back, not always to win, but he’s kept them competitive. I’ve seen him make six or eight tremendous throws. He has a cannon. He’s not as athletic as some of the other guys we’re talking about, but if you’re looking for a tough guy with a rocket arm, Weeden might be for you.

So those are the five starters. Who’s going to be the sixth rookie quarterback to emerge?

I had [Philadelphia’s] Nick Foles in the preseason against New England. Michael Vick got hurt on the fifth or sixth play, and Foles went the distance, on the road in Foxborough. If you like prototype pocket passers with some functional mobility and a tremendous amount of toughness, Foles is interesting.

What really impressed me in the preseason was they weren’t running generic formations. They ran about 30 different formations out of about eight different personnel groupings in successive plays. So I see him recognizing coverages. I see him getting to second and third receivers, just like you’d want a quarterback to do in that system, and I love his NFL size. He reminds me a lot of Brad Johnson, from his football character to his ability to decipher a lot quickly, and we won a championship with Brad.

sam.farmer@latimes.com

Twitter: @LATimesfarmer