Isaiah Thomas, now a Nugget, was all-in with Boston, including helping to recruit free agents.

Isaiah Thomas has agreed to a one-year, $2 million minimum deal to join the Denver Nuggets. It will be his third team since being traded from Boston in the Kyrie Irving deal late last August, but his fingerprints are still on the Celtics.

Had Thomas not come to the Celtics in February 2015, dragged them into the playoffs that year, and led them from 40 wins that season to 48 and 53 in the ones that followed, the Celts may never have been viewed as attractive enough to free agents. Maybe Al Horford and Gordon Hayward come anyway, but they would have been looking at a far less successful club and had to take a far greater leap of faith. And Thomas was obviously a big part in getting Irving, even though injuries and other team issues made it a poor fit for him in Cleveland.

Some Boston fans have expressed ire with Thomas for being open about wanting a big contract (he would smilingly talk about the Brinks truck when asked) and the whole tribute video mess that never should have been a big deal. But there’s strong evidence that the Celtics aren’t where they are now – favorites to win the Eastern Conference this coming year – if Danny Ainge doesn’t steal him from Phoenix 21/2 years ago (you also got Jonas Jerebko out of that deal).

“Isaiah added credibility to our team by making us a legitimate basketball team,” Ainge said. “On top of that he was very entertaining.

“But he was all-in. He was all-in for the team. He was recruiting Al Horford to come. He was recruiting Gordon Hayward to play with him. He’s earned a lot of respect in my eyes.

“He was a big part in the perception of our team at that time, no doubt.”

The Celtics were 12 games under .500 when they traded for Thomas and went 20-10 the rest of the way with Thomas scoring 19.0 points to lead them. He threw in 22.2 and 28.9 in the ensuing seasons, giving the Celtics guaranteed scoring as they climbed the East ladder.

“I would say that Isaiah did a lot for our franchise,” said Ainge. “He did a lot for the entire organization. He did a lot for our coaches and players. He took a lot of pressure off everybody because he was a dominant offensive player for 21/2 years.”

And more.

“He entertained our fans. He competed at a very high level. He was tough as nails, and he was a big-time fourth-quarter guy,” said Ainge. “He brought a lot of electricity and excitement to the Garden.

“I’ll always be grateful for Isaiah. And on top of that I loved him as a kid. Him and his wife, Kayla, they’re two of my favorite people. They were a joy to be around.

“Isaiah was all-in. I’ll always be grateful for that. He was all-in. He was 100 percent in for the Boston Celtics when he was here. And he was that way in Sacramento when he was the 60th pick. He was all-in there, and I think that’s probably why Coach (Mike) Malone wants him back (Malone is now the coach in Denver). But I thought Isaiah was a good teammate. He was a good Celtic.”

And he impressed others around the league.

When Thomas’ agreement with the Nuggets hit the news, Dwyane Wade tweeted, “I. Can’t. Wait. @isaiathomas go do what you’ve done your whole life and that’s make everyone swallow their words. They can’t measure your heart cuz!”

Evan Turner, now a Trail Blazer but a teammate with Thomas on the Celts, tweeted, “I.T. About to be the man again. He’s going to get the nuggets to the playoffs, for sure!”

Certainly Thomas is in the right place to get his game and reputation back after fighting last year through the hip injury he suffered with the Celtics. Malone is an Isaiah believer.

“He was a guy that trusted me from the jump,” Thomas said two years ago when the Celtics were in Denver. “He believed in me, and when he was able to coach me he allowed me to play through mistakes, allowed me to be myself and someone that was 100 percent real with me from Day 1. So someone that I’m really close to, and we talk to this day.”

Ainge said while the basketball side of him obviously had to make the trade for Irving, it was hard to see Thomas go.

“Are you kidding me? That was very difficult,” Ainge said. “You know, making the deals for Isaiah and Avery (Bradley) were two of the toughest things I’ve had to do in this job. I’ll always have a fond place for those guys and root for them and cheer for their success. But yeah, those were two hard moves to make.”

Yet a bit of Thomas remains because of the hand he had in what the Celtics have become.