INDIANAPOLIS – In NFL advanced mathematics, Leadership + Presence + Charisma = It.

Even so, it can be difficult to define.

“It’s hard to really put into words,’’ said Frank Reich, who possessed it during a 13-year NFL career as a trusted backup quarterback. “I guess that’s why we call it, ‘it.’’’

Usually reserved for when discussions turn to quarterbacks, it refers to whether players respond to his words and actions, both on the field and in the locker room. Do players – offense, defense, whichever meeting room they frequent – consider him their undeniable leader? Does he bring that aura to the huddle that even though the team might trail by 17 points in the third quarter or by one score with 50 seconds remaining, there’s every reason to believe a comeback is possible, even likely?

Does everyone believe in him? Do they trust him? Does he exude confidence?

Do a quick survey of the Indianapolis Colts and the consensus is Matt Ryan has it.

What’s it like when Ryan addresses the team? Remember, he’s still one of the newbies – he was acquired in a trade with Atlanta March 21 – but is 37 and entering his 15th season.

It appears the room grows quiet and players pay attention.

“I can’t describe it. You just get chills,’’ said running back Nyheim Hines. “He starts talking to us, and you just look at him and go, ‘OK, this guy is about to lead up to a championship or to (the) AFC South and lead us as far as we want to go’.

“He has been there. He has been to the Super Bowl and I don’t know how many guys have been to the Super Bowl on this roster – probably less than 10 – but we are looking at those guys to lead us because we haven’t been there . . . guys who are becoming older now, we want to win.’’

Zaire Franklin’s assessment comes from a dramatically different vantage point. He’s a starting linebacker. His Colts’ career has exposed to him to five different starting QBs: From Andrew Luck to Jacoby Brissett to Philip Rivers to Carson Wentz and now to Ryan.

“Matt’s cool,’’ he said. “He’s mad charismatic. Matt just wants to be like one of the guys, so he is looking to come and do his work and push himself and push the team so it’s great to have him around.

“From a defensive perspective, when you have a veteran QB like that you know is going to make the right reads, know is going to make the right plays, know is going to make sure everyone is in the right spot, that just makes you go get it. That makes you more aggressive. It makes you want to attack.’’

As Reich stressed, when a quarterback possesses the requisite traits – and let’s not kid ourselves, also plays at a high level – “the team just gravitates. You feel it from the team. You sense it from the team. You sense a confidence from the team and I think that’s where we feel right now with Matt as our quarterback.

“He’s just come in here in every way physically: the way he’s throwing the ball, the way he carries himself and what he has meant to this team and what he’s said to this team. We’re just at the beginning of the road, but his experience and his leadership . . . I think we’re all feeling it.’’

The knee-jerk reaction to the euphoric atmosphere that’s followed the Colts into training camp at Grand Park Sports Campus probably is in large part because Matt Ryan isn’t Carson Wentz. One of the overriding reasons owner Jim Irsay determined his organization would cut ties with Wentz after one failed season – a failed season by Wentz and by the entire team – was because of a lack of leadership on Wentz’s part.

As players have addressed Ryan’s presence, they’ve been careful not to contrast him with Wentz.

Safety Julian Blackmon has been impressed by Ryan’s “game management.’’

“He’s a really good leader, not to take anything away from anyone in previous time,’’ he said. “He’s got an idea of what he wants to do with the offense and he does it.’’

Ryan has heard the comments from his new coaches and teammates – how could he not? – but insisted he’s not gone off script to prove he’s the leader the franchise has missed since Rivers in 2020.

“I’ve never tried to be anything other than myself and you know, I’ve always just felt like the work that you put in daily is the ‘it’ factor,’’ he said following Wednesday’s first practice. “It creates the confidence from other guys. You try to set the standard for how to do it and I’ve always been comfortable trying to get the best out of my teammates and trying to make them the best individuals they can be so we can be the best team we can be.

“Other than that, I don’t really overthink it. Work hard every day, be yourself and try to pull guys up to the level that they’re capable of getting to.’’

Ryan started 222 of 225 regular-season games in 14 seasons with the Falcons. He experienced the highs (2016 NFL MVP and taking the Falcons to the Super Bowl that season), lows (four consecutive losing seasons) and everything in between.

He realizes there are countless ways to prove to teammates you’re a leader, whether it’s vocally or by performance. There are fire-and-brimstone guys and the strong, silent types.

“I think good teams – at least the good teams I’ve been on – have collective leadership,’’ Ryan said. “I truly believe that different styles are really good. It pulls the best out of multiple guys, and we certainly have that in our locker room.’’

Occasionally, Ryan’s leadership skills are put to the test. Occasionally, a team might lose its focus over the course of a long season.

Then what?

“Keep a foot up their ass,’’ Ryan said with a smile. “You know, just when they need it.’’

Left foot? Right foot?

“Whichever is closer. It’s both,’’ Ryan said. “Sometimes it’s letting guys know that we need better. Sometimes it’s a little love, too. Each guy is different, each day is different, but the beauty of experience is you kind of know when it’s not right. You have that sense of when things are right.

“The thing I’ve learned is that you need to nip that in the bud as soon as possible and you need to get it back to where it needs to be. I try and do the best I can do. We also have a great coaching staff, too, guys that have great experience and understand what it looks like at the highest level and that’s going to help us.’’

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You can follow Mike Chappell on Twitter at @mchappell51.