LAS VEGAS — Bobby Portis, the Knicks’ new 6-foot-11 backup power forward, says all the players knew back in February that Kevin Durant and Kyrie Irving were headed to Brooklyn.

It seems hard to fathom, but Portis says he had “sources.”

“I knew what was gonna happen in February,” he reportedly said courtside during a summer league game Saturday. “We all knew that [Durant and Irving would join the Nets]. Everybody knew that. I just don’t think the media knew that. Us basketball players, we all knew that.”

How much Knicks president Steve Mills and GM Scott Perry knew is also a mystery. They have yet to address the media since free agency began, nor have they officially announced the Portis signing or the other five free-agent signings.

Mills released a statement June 30 that acknowledged fans “could be disappointed’’ by not landing a superstar but they “continue to be confident and upbeat.’’

Knicks brass had given plenty of warnings that the team may not land the big fish in the final two weeks leading into free agency despite an ESPN report that quoted an agent saying, “Just a matter of putting pen to paper.’’

Portis was a restricted free agent, but the Wizards couldn’t compete with the Knicks’ wild offer for two years, $31 million, even though the second year is non-guaranteed.

Portis is mostly viewed by NBA personnel men as a backup power forward and center as he’s not considered a good defensive player. Neither is their other big power-forward signing, Julius Randle.

Still, Portis is known as a workout demon and should bring a lot of activity and spirit to a club that stumbled to a 17-65 record last year. His temper got the best of him two years ago when he punched out then-Bulls teammate Nikola Mirotic after a practice.

A less-celebrated incident came a season before that with Dwyane Wade during his forgettable stint in Chicago. The Post reported last week Portis stood up to Wade after Wade ripped his young teammates in a meeting. Portis told Wade never to question his work ethic.

“I did stand up to him and just say that,’’ Portis confirmed. “He was just trying to call some of my teammates out and call us out about how we don’t work, this and that. The moral [of the] story is that I’m a guy that brings it each and every day, comes in early, leaves late, works hard. I am the underdog. Everybody counted me out, and I kind of embrace that.”

Randle talked about bringing some toughness back to the Knicks and Portis said the same.

“I just know that every team I played on hasn’t been a soft team,” Portis said in an online interview. “I just try to go out there and bring an edge, bring a competitive spirit and be myself. Be like the enforcer a little bit. Hard fouls. Nothing easy. Play hard and play smart as well. We’re not trying to hurt anybody, but we do want teams to know that when they come play us that the Knicks are there.”

Portis believes rookie lottery pick RJ Barrett will fit right into that mold and mindset.

“I saw him a lot at Duke,’’ Barrett told NBC Sports Chicago. “Obviously I watched a lot of Duke basketball with him and Zion [Williamson]. Really entertaining to watch. He’s a highly competitive player. He goes out there and plays with an edge. He has swagger, too. He’s very confident in his game. He’s going to be a great player.”