Kenny Atkinson went through a winless preseason with the Cleveland Cavaliers and wondered if his team would be any good.

Turns out, they were better than good.

And their coach — he was the NBA’s best this season.

Atkinson is now an NBA Coach of the Year winner, announced Monday night as this year’s recipient of the Red Auerbach Trophy. Atkinson led Cleveland to a 15-0 start to the season — one of three winning streaks of at least 12 games this season by his club — and led the Cavaliers to the best record in the Eastern Conference.

“I stepped into this,” Atkinson said. “I keep saying that, that I stepped into this. It’s a little bit of luck too, right?”

J.B. Bickerstaff was second in the voting, after pulling Detroit from the basement to the playoffs. Ime Udoka was third, after guiding Houston’s path to ending its five-year playoff drought.

All three did elite jobs this season. But none better than Atkinson.

All were coach of the year candidates previously. Bickerstaff has gotten votes now in each of the last four seasons, Udoka has gotten votes in all three of his seasons as a head coach and Atkinson finished fifth in the voting for the 2018-19 season, when he coached Brooklyn.

This was the best finish in the voting for each of this year’s finalists. And for Atkinson, it was a sweep: He also won the National Basketball Coaches Association’s coach of the year award, one that is separate from the official NBA award and is voted on by other head coaches.

“I almost broke down when I got that,” Atkinson said. “Like, to think (Rick) Carlisle voted for me, that (Erik) Spoelstra voted for me ... that’s like the pinnacle.”

Atkinson won the NBA award. unveiled Monday night on a TNT broadcast, by a comfortable margin — getting 59 of the 100 first-place votes and appearing on 99 of the 100 ballots. Bickerstaff got 31 first-place votes to finish second, while Udoka got seven first-place votes to finish third.

Oklahoma City’s Mark Daigneault (two first-place votes) was fourth. Tyronn Lue of the Los Angeles Clippers got the other first-place vote and finished fifth, and JJ Redick of the Los Angeles Lakers was sixth.

Atkinson went to the Cavaliers after spending the most recent three seasons as an assistant with Golden State under Warriors coach Steve Kerr.

Atkinson and Bickerstaff both flourished in Year 1 of their current stints.

Atkinson led Cleveland to a 64-18 record and the No. 1 seed in the East — doing so after Bickerstaff got fired following a run to the second round in Cleveland last season.

Bickerstaff was then hired by Detroit and turned a 14-win team into a 44-win team that earned the East’s No. 6 seed.