New England head coach Bill Belichick celebrated with Jon Bon Jovi in Foxborough after the Patriots defeated the Steelers 36-17 to win the AFC championship. Patrick Smith/Getty Images

Bill Belichick has only two modes. There's the version everyone knows: the intense, maniacal emperor, prowling the field, whistle whipping around his fingers, eyes peering out from beneath that hoodie, ready to rip his Hall of Fame quarterback as quickly as a practice squad rookie.

And there's the other Belichick: "When Bon Jovi was there," former Patriots linebacker Rosevelt Colvin says, laughing. "Then he couldn't care less what was going on."

"When Bon Jovi was there ... he couldn't care less what was going on." Former Patriots linebacker Rosevelt Colvin

Forget, for a moment, trying to figure out how the Patriots' defense is going to slow down Atlanta's epic air attack. Forget how the Falcons' young D plans to disrupt Tom Brady. Nevermind about whether the Patriots are the greatest franchise ever (or the most corrupt).

The real mystery of Super Bowl LI is this: What's up with Bel Jovi, the strangest bromance in sports? Why is the greatest (arguably) football coach of all time so smitten with one of the worst (arguably) rock bands in history?

This wonderfully weird Bel Jovi pairing dates to the 1980s, but it was on full, vomitous (to quote a colleague) display during the second half of the AFC Championship Game at Gillette Stadium. That's when the coach, normally so focused on the game that he can't even bother with sweatshirt sleeves, paused during the biggest game yet of the season. As the crowd sang along to Bon Jovi's "Livin' on a Prayer," Jon Bon Jovi himself sang and bro-pointed to the crowd and his beloved coach from the warmth of a luxury box.

When it mercifully ended, I thought: Well, that's that. Surely the "we're on to Cincinnati" coach would have nothing to say about something as trivial as the Bel Jovi sing-along.

If only.

"Yeah, I was definitely aware of it," Belichick said, prompted by ESPN's Mike Reiss, before morphing into a teenager right there at the podium. "Jon, I mean I've heard him play that song dozens of times, but he had that place rocking, maybe a little more than we did. Yeah, pretty impressive. He's a great friend, been a friend for a long time all the way back into the '80s.

"We've shared a lot of great moments together, including the 1990 Super Bowl [with the Giants] in Tampa, where he was in the locker room after the game still taking crazy pictures and stuff like that; great memories from there. It was great to have Jon here, and I always appreciate his great support. Yeah, it was quite a moment, one that you usually don't see at a professional football game. It was special."

Uh, not really.

Belichick greeted Jon Bon Jovi before a 2015 game against the New York Giants at MetLife Stadium. Robert Deutsch-USA TODAY Sports

Normally when teams on championship runs adopt cheesy theme music from, say, a band like Journey, it's tongue-in-cheek, in a this-is-so-bad-it's-good way that almost makes it tolerable. Not that crowd in Gillette. Not Bel Jovi. They all belted out that tinny tune without an ounce of irony while the rest of the world cringed as if watching our tipsy parents do the YMCA at our wedding reception. Falcons fans were not laughing with you, Patriots Nation. They were laughing at you.

I mean, poor Gronk. He obviously knows the song, because he croaked out an unlistenable version in a commercial for "Madden NFL 17." But standing next to Bon Jovi in the suite at Gillette, I thought he might seriously pull a muscle restraining himself from a giggle. Gronk's not alone. Trust me, the most common response you get when asking Patriots players about Bel Jovi is an extended eye roll. (Of course, if you've seen the YouTube gem of Belichick and Charlie Weis singing backup on "Wanted Dead or Alive," then you know last week in Foxborough was the second-worst Bel Jovi video of all time.)

We should pause here for a moment and say that if you dig Bon Jovi, that's awesome and more power to you. After all, the sign of a true fan is someone who fully loves and supports a team, or a band, without worrying a single moment what some guy who owns a St. Vincent tote bag thinks. (One thing that isn't up for debate: I'm not sure any band can match Bon Jovi's tireless and massive charitable works.) You shouldn't care that the closest Bon Jovi has ever come to the Rock & Roll Hall of Fame was attending Browns practice when Belichick coached in Cleveland. Or that a critic once said he "philosophizes like Forrest Gump in leather pants."

This is the point in the column when you tell me Bon Jovi has been selling out stadiums for decades. To which I say, so have the Browns. And then you reference the band's 800 million albums sold. To which I say, have you seen the DirecTV ad?

"This is the point when you tell me Bon Jovi has been selling out stadiums for decades. To which I say, so have the Browns."

Look, "Runaway" is a quality song that helped birth the whole pop-hair-metal thing. And his hair was glorious, I'll give you that. And you simply can't deny the catchy staying power of "Livin' on a Prayer" and "You Give Love a Bad Name." Who among us hasn't wondered if Tommy ever worked things out with his union, or if Gina ever made it out of that diner? But after that? "Lost Highway" works better as a Bon Jovi metaphor than a song. "Lay Your Hands on Me" could have been on the Spinal Tap soundtrack. It's bad enough that "Bed of Roses" is nearly impossible to differentiate from "I'll Be There for You," or "Blaze of Glory," or a half-dozen other JBJ songs, but it also contains lyrics -- With an ironclad fist I wake up and; French kiss the morning -- that make Justin Bieber sound like Leonard Cohen.

The guy's no Dylan, right? And I guess that's my point. I agree with the Rolling Stone critic who once wrote that hating Bon Jovi seems silly at this point. But even Bon Jovi fans have to wonder, from time to time, how in the world a guy like Belichick ended up such a fanboy. It defies logic. How could a cynical, hard-nosed coach end up with a Hall of Fame career soundtrack that includes "Have a Nice Day"? How does the singularly focused "Do Your Job" guru hook up with the hair-metal/pop-metal/country music singer who moonlights as an AFL owner, was an extra on Ally McBeal and is a pasta sauce tycoon?

You guys in New England hate everyone, and that's kinda what we love about you. But you make an exception for this guy? You could have adopted Aerosmith, which is actually from Boston. Really, you guys could have picked anyone. But you went with Bon Jovi, a guy from Jersey who grew up a Giants fan, who owned an Arena League team in Philly and who was actually boycotted in Buffalo after he tried to buy the Bills? It's like Bruce Springsteen playing a show at MSG in a Jay Cutler jersey.

Jon Bon Jovi was said to be the most hated man in Buffalo while leading an unsuccessful bid to buy the Bills in 2014. Here, a Bills fan holds a protest sign during a preseason game against Pittsburgh that August. AP Photo/Don Wright

Bel Jovi formed in the 1980s, while Belichick was spending 10 years as an assistant coach with the Giants under Bill Parcells. Belichick started as a special-teams coach. At the time, Giants punter Sean Landeta was a Bon Jovi nut, and one thing led to another. After helping the Giants win two Super Bowls with his defense, Belichick took the head-coaching job in Cleveland, and Bon Jovi became a regular at Browns practice, catching passes and strolling the sideline with the coach.

Coaches from his Cleveland staff describe Belichick back then as a true rock music fan. They say he was a loyal Howard Stern listener and that he followed the Rolling Stones around Europe during one offseason. He even invited the entire coaching staff, including Nick Saban, to his luxury box at a Cleveland arena for a Pink Floyd show. (Saban, Belichick and Roger Waters? If they ever invent time travel, I'm headed straight back to that night in Cleveland.)

"Bill's a real closet rock 'n' roll nut," says former Browns assistant Rick Venturi. "I didn't see him with his lighter out [at Pink Floyd], but it wouldn't surprise me if I did."

Based on his public persona, wouldn't you picture Belichick as a fan of the Stones, Pink Floyd, Van Halen or even Metallica? Or perhaps an uncompromising, loner genius who goes more for Johnny Cash, Warren Zevon, Iggy Pop or David Byrne?

But I guess if Belichick's wardrobe (Flashdance) and his politics (Reagan) stopped evolving in the 1980s, just as his coaching career was taking off, it makes sense that his taste in music would, too. I also suspect the Bel Jovi bromance is a reflection of something that people close to Belichick over the years have always suspected: the whole tough guy, Darth Vader thing is mostly an act.

Deep down, he's still that nerdy, second-string lineman and football film geek who, no matter how many championships he collects, can't believe the dude with the supermodel mane who flew over the crowd like a leather-fringed angel in that awesome "Livin' on a Prayer" video is actually one of his bestest friends.

And who can blame him?

All we really can do at this point is prepare ourselves. In a few days, when Belichick is holding up the silver Super Bowl trophy that should one day bear his name, don't be surprised when he caps this dynasty and this epic Bel Jovi bromance with a simple, fitting dedication.

This. One's. For. Gina.