One weekend morning this spring, Sam Darnold was in a New York City hotel room after a night out with friends when his phone rang with a FaceTime call.

It was Adam Gase.

“I’m like, ‘What’s going on?’ I’m in the hotel. I’m in my boxers. I have my shirt off and I’m FaceTiming my head coach,” Darnold recalled with a smile.

Gase quickly saw it was not a good time to chat and told Darnold to go take a shower.

“If you see his name pop up and Adam Gase wants to FaceTime you, no matter what you’re doing you always feel comfortable answering and he’s not going to judge you,” Darnold said.

The Jets’ second-year quarterback and first-year head coach have developed a strong relationship over their first eight months together. The franchise is counting on that relationship leading to more than just FaceTime hijinks, but to wins and eventually championships.

That is the reason Gase was hired in January over the other candidates interviewed. The Jets felt he was the right coach to bring out the best in their young quarterback. The two have spent the spring and summer getting to know each other better and learning to speak the same language, even if that requires the occasional FaceTime surprise from the head coach.

“I bug him a lot,” Gase said. “I FaceTime every once in a while and just drive him nuts.”

The head coach-quarterback relationship is the most critical in sports and it is at the center of the 2019 Jets. A baseball manager and pitcher do not always need to be on the same page. In basketball, star players have more clout than coaches. In hockey, a goaltender and coach do not need to have great communication.

But in football, it is essential. From Paul Brown and Otto Graham through Bill Belichick and Tom Brady, nearly every dynasty in NFL history has had a coach/ quarterback tandem leading the way. You look at a great quarterback, they usually have a great coach. You look at a great coach and they nearly always have a great quarterback.

Since 1967, there have been 18 coaches inducted into the Pro Football Hall of Fame. Of those 18, only three of them did not have a Hall of Fame quarterback.

In the current NFL, a group of second-year quarterbacks has recently had success in tandem with an offensive-minded head coach. The Rams (Jared Goff and Sean McVay), Bears (Mitch Trubisky and Matt Nagy) and Chiefs (Patrick Mahomes and Andy Reid) all went to the playoffs in that quarterback’s second year. The Jets hope Gase can do the same with Darnold. That is why they made him their first head coach with an offensive background since Rich Kotite in 1996.

“I don’t want to say it has to be a great relationship, but you have to have an understanding,” Hall of Fame coach Bill Parcells said.

Parcells had one of the great coach/quarterback relationships in New York history. There are three that come to mind over the past 60 years — Parcells and Phil Simms with the 1980s Giants, Weeb Ewbank and Joe Namath in the 1960s and early 70s with the Jets and Tom Coughlin and Eli Manning in the 2000s with the Giants. All won at least one championship together.

Parcells and Simms had a fiery relationship that both said was fueled by their competitive spirit.

“Bill and I spoke the same language,” Simms, now a CBS analyst, said. “I know everybody says, ‘You two argued.’ We spoke the same language. We were the same guy. That’s why we got along. That’s why we could yell at each other.”

Parcells agreed when relayed Simms’ comments.

“He was a pretty fiery personality and so was I,” Parcells said. “But it was OK, we weren’t taking things personally and there were times when we could have but we didn’t.”

Gase and Darnold are not at the point of yelling at each other on the field yet. They are still feeling each other out.

At one point in OTAs this spring, Gase yelled at Darnold. The 22-year-old quarterback told him, “It’s about time.”

“He’s always cracking jokes left and right,” Darnold said. “I’m still trying to figure out how much I can say to him. I don’t want to be like saying things that aren’t appropriate with him being the head coach and everything. It’s all fun and games until you make fun of the head coach.”

The two are also trying to learn how to communicate about football together.

“The other night he swings in and I kind of showed him how I watch film, how I go through game planning,” Gase said. “We talked though what’s the best way for you to do it. I think that’s going to be an ongoing process for him and myself because I don’t want to overload him and having him looking at all the stuff when he doesn’t need to. It’s one of those things where Year 2 is going to be different than Year 8 for him. We’ve just got to slowly keep building that library up.”

Darnold said he and Gase process things similarly and that has helped him learn the offense. Gase texts him at night about the next day’s practice and the two seem to always be talking when they are on the field.

Gase said he will involve Darnold in game-planning to make sure the quarterback feels comfortable with what they are doing. That is something Parcells did with the Jets when Vinny Testaverde was his quarterback in 1998.

“Vinny did not like confrontation,” Parcells said. “I understood that. When we were doing something, all I wanted to do was make sure Vinny liked what was in the game plan. If he didn’t like certain things, we’d just throw them out. I would say, ‘Is everything here OK?’ As soon as he said, ‘OK, coach,’ well then he owned it. We were all calling the plays with the confidence that he liked them and we thought we could execute them.”

Hall of Fame quarterback Dan Fouts said it will be different for Darnold to have a head coach who is invested in the offense and the quarterbacks room. Todd Bowles was a defensive coach and the de facto defensive coordinator for much of last year.

“It’s huge,” Fouts said of that relationship.

Don Coryell was hired to coach the Chargers midway through the 1978 season, Fouts’ sixth season in the league. The next year Fouts went to the first of six Pro Bowls and was All-Pro for the first time.

“He gave me hope, a tremendous attack plan and a commitment,” Fouts, now a CBS analyst, said. “I tell a story about starting a game and missing my first three passes and my fourth one was picked off for a touchdown the other way. I come over to the sideline and instead of feeling like I’m going to get yanked, he says, ‘You’ve got 40 more throws, OK?’ It’s that commitment to the plan, to the offense and to me that was the reason we had success.”

Beyond calling good plays, giving the quarterback that belief is where the best coaches make their marks, several former quarterbacks said.

“Confidence is an unbelievable thing,” Simms said. “You can conquer all. A tight throw looks wide open all of a sudden. You’re a better decision-maker. You feel good. You lead better. When you eat at night, it goes down easier. All that’s real. The better he manages Sam Darnold, the better it’s going to be for the whole football team.”

Gase famously worked with Peyton Manning, one of the greatest to ever line up, when he was with the Broncos. Gase said the biggest thing he learned from Manning was how to listen to players. He is now trying to forge a relationship with Darnold in which the quarterback can always have a direct line to him on anything.

“Is it really important for Sam? [Expletive] yeah,” Gase said. “Think about it, he can come to me for anything. It might be the smallest thing that somebody else is griping about and he can be like, ‘Hey, we really need to get this fixed because this group is having a problem.’ He can solve problems. He can get to me where some guys might be a little afraid to say anything. He knows like, ‘We need to get this fixed.’ He wants to win. For him to do that, he needs to make sure that crew is good.”

Darnold knows he can reach Gase at any time about anything, even if it is a Sunday morning FaceTime call in his boxers.