A day after losing their opener to the Bills in heartbreaking fashion, the Jets were trying to figure out what went wrong, fix the problems and then move on.

“We made some mistakes and they were fatal for us,” Jets coach Adam Gase said. “We couldn’t take advantage of the opportunities that we had. If we would have, we would have had a different outcome, but that’s every game.”

The Jets were left lamenting what could have been after they blew a 16-0 lead in the second half and ended up falling 17-16 to Buffalo.

The loss came despite forcing four Buffalo turnovers in the first half and shutting down the Bills for 2 ½ quarters. The offense failed to take advantage of the defense getting those turnovers early and then could not come through late when it got the ball back with three minutes left and the game on the line. The defense fell apart in the fourth quarter without inside linebacker C.J. Mosley, who left with a groin injury. The Bills responded with 17 unanswered points to drop the Jets to 0-1 to start the season.

“When we hit the fourth quarter, when we hit nut-cutting time, it’s the time when things are really getting tough, when it’s really getting hairy, the best players don’t change,” Gase said. “The players that make an impact in the fourth quarter, they don’t change, everyone else does.

“That guy plays the same in the fourth quarter as he does in the first quarter. The guys that panic and play different in the fourth quarter, that’s the thing we have to clean up. We have to get it to where we play the fourth quarter the same as we play the first quarter.”

Gase was critical of his team in several areas:

— Without mentioning wide receiver Robby Anderson by name, he referenced a play on which Anderson got open with 1:35 left to play but slowed down and Sam Darnold overthrew him: “We had opportunities. We had a chance to win the game. We’ve got to come out of our double move, the guy falls down and we don’t come out running. If we do that, then all of a sudden we’re scoring a touchdown. Guys need to do a better job of executing what they’re supposed to be doing.”

— On the wide receivers creating problems for the offensive line: “I would say that some of it was the O-line, but I would say if we read the coverages correctly with the receivers, some of that isn’t a problem.”

— On the defense’s fourth-quarter collapse: “We didn’t handle the fact that we lost our middle linebacker very well. That was something we addressed today. Basically, we need to understand when we lose somebody the next guy has to step up. We can’t have any loss of energy. We can’t lose our minds. It’s one of those things where it’s easier said than done but we have to understand that’s what we have to do. That’s our job.”

— On the cornerbacks: “I feel like we have slight room for improvement. I’ll say that nicely.”

— On the offensive line: “I felt like we got a little sloppy. What I mean by that is we were almost too aggressive. We were trying to be violent. We were trying to impose our will. I think it got us every once in a while.”

Gase said that after watching the film, Darnold played better than he initially thought.

“He did a lot of really good things. We’ve just got to clean a few things up,” Gase said. “That’s to be expected, especially the first time out against that defense. I was encouraged after watching the film. It felt different during the game and after going back and watching it I feel a lot better about how he performed.”

The Jets have to shake this loss off before facing the Browns on Monday.

“That one stung everybody,” Gase said. “Anytime you lose a close game like that it hurts. I like the way these guys came in today and have been working. It’s going to be about getting back to the 0-0 point and getting ready for the next one.”