What Charlie Weis knows for sure is that Brian Daboll can take it.

What happens next is anyone’s guess. But Weis — who was with the Patriots when Daboll got his start in the NFL — knows the new head coach of the Giants can handle all that comes with a most demanding job.

“There are questions like ‘How do you handle adversity?’ especially in the New York market, how’s that gonna go?’’ Weis told The Post on Saturday. “How do you deal with the media in the New York market? Until you get the opportunity to do that, there are gonna be unknowns no matter who you end up picking.

“He’s been hardened. Sometimes we talk about people who are soft. He’s not soft. He’s been hardened.’’

Daboll’s first NFL experience was with Bill Belichick. His first, and later his most recent, college experience was with Nick Saban.

“We coach hard up there in New England, Bill’s really hard on his staff,’’ Weis said. “You look at Saban, you know Saban was hard on him while he was there. You watch Nick just hammering the coordinators all the time. He’s been hardened.’’

Weis is not a bystander to this hardening process. When he said Daboll can “take a lickin’ and keep on tickin’ ” and when he insisted, “He can take a verbal beating,’’ that assurance is not based on observation.

“I’ve done it!’’ Weis said. “What do you mean have I seen it? I’m guilty as charged. I’m one of the people I’m talking about. He had mental toughness and he had it when he was young, too.’’

Weis was the Patriots’ offensive coordinator in 2000 when Daboll was hired as a defensive assistant. Two years later, Daboll was elevated to wide receivers coach, which meant he worked directly with Weis and was stationed in the office right next to Weis. Daboll, now 46, was in his mid-20s and embarked on a 21-year NFL coaching rise that took him through the Jets, Browns, Dolphins, Chiefs, back to the Patriots and Alabama. The past four years, his work with the Bills and Josh Allen made Daboll the hottest of candidates.

“We’re talking about a lot of years,’’ Weis said. “Sometimes I would get jealous of guys who got jobs who I thought got jobs that they hadn’t earned. They just seemed to get handed jobs. I always felt the jobs I got I had to earn. I think Brian has definitely earned this job. Sometimes you second-guess a pick, even though there were really good candidates they were interviewing, no one could second-guess that Brian Daboll has earned this opportunity, because he has. You take the last half-dozen years and say, ‘Has there anyone else where the arrow was pointing up any higher than his?’ I think you’d have a tough task coming up with somebody who was any better. Maybe even, but no better.’’

Weis said his first impressions of Daboll were that he was bright, hard-working, came up with good ideas, was energetic and had a positive personality. He said Daboll can “be ornery, like everyone else’’ but figures Daboll will have no issues handling the New York media.

This is the step that trips up so many coordinators, the step that Daboll now takes.

“Let’s face it, this is the New York Giants, the biggest market in the country,’’ Weis said. “Can he command the room? He’s been commanding half the room for the last bunch of years. He’s been a coordinator the last bunch of years. That’s commanding a room with a bunch of men, not just kids.’’

Weis believes Daboll is ready for this, and that he can take all that comes with it.