Ben McAdoo rose through the ranks to become an NFL head coach before he turned 40, largely on his ability to assess and develop quarterbacks. Most everything went awry for him and the Giants in 2017, but that should not discount McAdoo as a keen evaluator of the most important position on the field.

With time to kill and a desire to stay close to the game after he was fired with four games remaining last season, McAdoo took it upon himself to scout the top quarterbacks entering the 2018 draft. He rated Josh Allen of Wyoming as the best of the bunch — new Giants coach Pat Shurmur also had Allen No. 1 — but, overall, McAdoo was not enamored of this class of quarterbacks.

“There was no Andrew Luck coming out, no guy head and shoulders above everybody else,’’ McAdoo told The Post.

That is not the most encouraging news for the Jets. McAdoo wonders if Sam Darnold, taken No. 3, will ever be the franchise-saver the Jets need him to be. McAdoo could not get past flaws in Darnold’s throwing mechanics and his ball security.

“I think the kid the Jets drafted has a lot of magic in his game,’’ McAdoo said. “I think he’s special. He’s obviously a talented guy, he can make plays with his feet. I’d just have a hard time drafting a guy in the first round where you don’t necessarily like the way he throws.

“He can overcome it, guys have, but that’s something that’s a challenge for me. I’m gonna be looking at that, trying to fix it, because it’s a fundamental flaw, and I believe in the fundamentals. The quarterback, his No. 1 job is to pass the football. If I don’t like the way he throws the ball, I have a hard time picking him, right?’’

McAdoo had Allen — taken by the Bills at No. 7 — at his top quarterback based on his “high ceiling.’’ His second-rated player was Lamar Jackson of Louisville, who went No. 32 to the Ravens. He put Darnold slightly ahead of Josh Rosen — who went No. 10 to the Cardinals — based on Rosen’s durability concerns.

“If he stays out on the field he’s probably going to be a helluva player and he’s probably going to be the most ready to play,’’ McAdoo said of Rosen. “I don’t worry about the other stuff they say, the leadership stuff, that’s all B.S. Aaron Rodgers was not all that. I don’t want a nice guy. Between the lines on Sunday, you give me a prick, I’ll take him.’’

McAdoo worked with Browns general manager John Dorsey when the two were together in Green Bay and said “I have a lot of respect for how he looks at players.’’ Still, McAdoo sounded a bit mystified Dorsey made Baker Mayfield the No. 1 pick in the entire draft. McAdoo had Mayfield as his sixth-rated quarterback (Mason Rudolph of Oklahoma State was his No. 5).

“He’s got an edge to him, I like that. He’s gonna lead, they’re gonna follow him,’’ McAdoo said of Mayfield. “I didn’t see a lot of pro-style football in his college tape. And if you’re short you have to be able to make up for it some way, somehow, and personality doesn’t do that.” I didn’t think he was a great athlete. This guy is kinda like a pocket quarterback that is short and with small hands, that’s what I worry about.’’