Sam Darnold of the Jets in the first quarter against the...

Sam Darnold of the Jets in the first quarter against the New England Patriots at MetLife Stadium on Oct. 21, 2019. Credit: Jim McIsaac

After the debacle that was Monday night’s 33-0 loss to the Patriots, Sam Darnold will be the Jets’ biggest source of concern in Sunday’s game against the Jaguars.

From his head down to his toes. Literally.

His head was swimming with confusion against Bill Belichick’s complicated defense. At one point, describing his inability to deal with the masterful coach’s schemes, Darnold said he was “seeing ghosts.’’ And it didn’t help that he spent much of the game dealing with a sore toe after being stepped on. The toenail was removed during the week.

Darnold insists his head is fine, that he’s ready for a solid bounce-back performance. And he says the toe is OK, too.

But if he is to successfully recover from a game in which he threw four interceptions and lost a fumble, it likely will come down to whether the connection between his head and his toes — or, more specifically, his feet — is working properly.

So much of any quarterback’s success relates to what he’s seeing and processing based on the opposing defense. If Darnold understands the concepts of how a team is trying to attack the Jets’ offense, his chances for success go up exponentially.

Such was the case a week earlier in a 24-22 win over the Cowboys; Darnold said afterward that he felt good from the start. In fact, he said he knew it would be a good day on his first drop-back, because as soon as he turned around to look at the defense, he immediately recognized what he’d seen from film study during the week.

But against Belichick, who has been confounding opponents with his intricate schemes for more than three decades, Darnold was lost. His head was swimming in bewilderment, and the confusion went right down to his feet.

While footwork often is the most overlooked and underappreciated aspect of a quarterback’s work, it was a glaring problem against the Patriots.

Darnold said much of the problem against the Patriots was in his head. That ultimately caused problems with his feet.

“Honestly, I think the biggest thing for me is I was thinking too much out there,” he said. “I wasn’t keeping things simple enough, I was trying to do too much, and when I do that, I get myself into trouble.”

Darnold was so befuddled by what he was seeing from the defense — whether he thought the Patriots were going to blitz and didn’t (or vice versa), whether he thought they were playing man defense or zone, or whether he couldn’t immediately figure out how to deal with the Patriots’ safeties — that he couldn’t properly set his feet on most of his throws.

His head was messed up, yes. But the confusion manifested itself in his feet.

It’s more proof why coaches spend an inordinate amount of time on a quarterback’s footwork so he’s properly balanced and in proper position to deliver his throws.

Sure, there are times when a passer must improvise, especially when dealing with a heavy pass rush. And Darnold already has shown that he can throw from what coach Adam Gase likes to call “different platforms,” or unusual positions based on circumstances that arise on a given play.

“It’s a work in progress for us,” Gase said. “It’s one of those things that it’s not a problem till it’s a problem. Even sometimes when he does throw from different platforms, we talk about, ‘Hey, your alignment, your footwork.’  ”

Darnold sometimes can be his own worst critic.

“[Darnold] is the one when he watches [film] like, ‘My feet need to be better here,’  ” Gase said. “Even in the Dallas game, there were times where he’s like, ‘My feet were terrible over on this throw.’ He completed [the pass], but he’s not even looking at that. He’s just saying, ‘My feet aren’t good.’  ”

His feet were awful against the Patriots. And if he’s going to not only bounce back from that nightmare but make continuous and consistent strides for the rest of his career, his footwork must improve.

Perhaps the greatest quarterback tactician in NFL history always made a point of making sure his quarterback’s feet were as accurate as his passes. When Bill Walsh helped turn around Dan Fouts’ career in San Diego before the coach moved on to Stanford, it was Walsh who drilled it into Fouts that his feet needed to be in unison in order to deliver passes more efficiently. Same with Joe Montana when the two started on their journey in 1979 as one of the great coach/quarterback duos.

It therefore is imperative that Darnold coordinate what’s going on in his head with what’s happening with his feet. That starts against a Jacksonville defense that boasts a formidable front seven featuring Calais Campbell, Myles Jack and Marcell Dareus. And that means recognizing the blitz much better than he did against the Patriots.

Jets offensive coordinator Dowell Loggains said it’s more than just Darnold who needs to be on point.

“We didn’t execute as a unit well enough,” he said of the disaster against the Patriots. “Sam’s fine. It’s not just on Sam. It’s on me. It’s on Adam. It’s on the rest of the coaching staff, it’s on every player to make sure. It’s not just one thing. There’s multiple things that keep happening that we need to clean up.”

Darnold is ready to get rid of the aftertaste of his worst game.

“Getting back out there and practicing with the guys, that’s how you get over losses like that,” he said. “But for me, it’s really about continuing to learn from that, continuing to learn from my mistakes I made in the Pats game, learn from it and have those mistakes not pop up again. I feel like I’m in a really good place right now.”

Darnold believes his head is right.

The proof will be in his feet.