Call him self-assured, cocky or both. Whatever it is, Cam Newton has never lacked self-confidence.

But on Thursday, Carolina’s quarterback let down his guard just enough to use words like “demoralizing,” “unacceptable” and “humbling” to describe the Panthers’ fall from NFC champs to NFC South cellar dwellers. It was a small but noticeable change for a guy who often attempts to exude an aura of invincibility.

The introspection only went so far, though.

Despite the drastic drop in his numbers from his MVP-winning season, Newton scoffed at the notion that his mechanics may again be out of whack.

“I look at even best quarterbacks that they said played this game, and mechanically, it’s not about that,” he said. “It’s about completions.”

Which doesn’t necessarily help his argument.

Newton’s 15-game pace comes out to 277 completions, which would be the second-fewest in his career behind 2014 when he completed 262 passes in 14 games. And, sure, it stands to reason he may not have as many completions in a year when he didn’t play a full schedule, but Newton’s seemingly regressed across the board.

He’s never been an accurate passer, but Newton’s current 54.7 completion rating is three percentage points lower than the worst of his career. His 80.6 passer rating is also a career low and a huge drop-off from the 99.4 he finished with last year. So are his touchdown and interception totals, which have gone from 35 and 10 to 14 and 8.

It hasn’t helped that Newton’s spent most of the season behind a badly battered line in an offense that hasn’t evolved much from a record-setting 2015. But how do you go from the best player in the league — one who can win 17 games with a receiving corps of Ted Ginn, Devin Funchess, Philly Brown, Jerricho Cotchery and Brenton Bersin — to what Newton’s been this season?

“I don’t know. It’s just me,” he said. “I can tell you it’s not because of preparation.”

Which is what some wondered while Newton spent the bulk of his summer in Los Angeles. Even though he fit in photoshoots, parties and his Nickelodeon show during his downtime, it created a new layer of criticism for arguably the NFL’s most-criticized star. So when asked if he was planning to play television producer again this offseason, Newton went on the defensive.

“Who knows? And if I am, I don’t think no one can tell me not,” he said.

“I’m a professional. Distractions come every single day — from family, from media, from workload.

“Life is bigger than football, so if you’re questioning certain things that I’m doing, I have a whole other list of requirements and duties that I need to take care of. Outside of football, I do have a life.”

And four days after standing up to his most important player, coach Ron Rivera was back to standing by his guy’s side

“I’m very confident and comfortable with the preparation. The things that a lot of people don’t see are the hours he puts in,” said Rivera, who then detailed the time Newton spends at the stadium during the week.

“That’s unfortunate and that’s disappointing that people draw conclusions based off other things. The young man’s dedicated, and when he comes here, it’s phenomenal.”

So if preparation isn’t an issue, what is?

That answer is apparently as mysterious as how the Panthers went from the Super Bowl to the league’s most disappointing team.

“It’s the luck of the draw sometimes,” Newton said.

“I understand we’re not having the season that we wanted to have, but it’s no need for people to just maliciously go out and say, ‘Well, he was doing too much, he was doing this, he’s worried about this, he’s worried about that.’ That’s the easy route.

“It doesn’t matter how much I prepare — if it doesn’t translate on the field, then people would just say, ‘Ah, he’s just garbage.’ So for me, it’s trying to get it to carry over from practice to games. And in this situation, in this season, it just hasn’t turned over and I don’t have nobody to blame but myself.”