LAS VEGAS – Today is a tough day. It’s hard to say goodbye.

Today, I, along with the Celtics organization and fan base, have to say goodbye to Avery Bradley.

No one wanted Avery to go. Everyone wanted him to stay. But as we all know, this is a business, and the Celtics must put franchise goals ahead of personal feelings. That’s part of Danny Ainge’s job description.

Trading Avery to the Detroit Pistons will free up the necessary cap space for the Celtics to sign a premier free agent who could very well alter the arc of the franchise for the next 5-10 years, and that arc may very well reach the height of Banner 18 and beyond.

But that doesn’t make saying goodbye any easier.

Avery and I didn’t come to the Celtics at the exact same time, but it was pretty darn close. I came to the franchise in March of 2009. Avery, meanwhile, was drafted in June of 2010.

I’ll never forget the day he was introduced as the newest member of the Boston Celtics, after he was chosen with the 19th overall pick during the 2010 NBA Draft.

It was the day after the Draft, on June 25, and Avery had already made his way to Boston to be introduced to the media alongside fellow draft pick Luke Harangody. The first thing I thought of when I met him was, “Man, he’s still just a kid.”

And he was. At 19 years old, and only one year removed from sitting in English class in high school, Avery was still growing, both from a physical and an emotional standpoint.

He was a quiet and humble kid, who sat at the podium in Waltham and gently spoke into the microphone as he answered the media’s questions. His answers were brief, yet honest and heartfelt. But boy, was he quiet and soft-spoken.

Fast-forward to today, and when you meet Avery, you don’t meet a kid. You meet a man.

I’ve watched Avery grow up, and it has been an absolute pleasure.

Avery went through some tough times during his tenure in Boston, which, by the way, had him ranked as the longest-tenured player on the team up until this trade.

He opened his career on the injured list with a bum ankle that became a problem during the lead-up to the Draft, that required surgery, and that forced him to miss training camp during his rookie season. That injury was a godsend, however, because had Avery never suffered that injury, he almost certainly wouldn’t have slipped to the Celtics at pick No. 19.

But he did, and then he joined a team that was in the heat of title contention. Paul Pierce, Kevin Garnett, Ray Allen and Rajon Rondo were two years removed from winning Banner 17, and they wanted more.

Doc Rivers was the coach, and he was never keen on giving young guys a chance. Avery was no exception.

Avery barely played during his rookie season as Doc unsuccessfully attempted to mold him into a point guard – which Avery is very much not – and that wasn’t easy on the young kid. Playing point guard was a massive failure, and riding the bench was a new role he had never been in before. Both of those factors stunted his growth as a player.

Soon enough, however, he would break through, and it was all because of his defense.

Doc said the night the C’s drafted Avery that the kid could walk in and make an immediate impact with his defense. We began to see that impact on a nightly basis during the second half of his second season, in 2011-2012, and that’s when things began to fall into place for Avery.

I’ll never forget the Jameer Nelson game, on Jan. 23, 2012. Avery never will, either.

Avery started at point guard in place of an injured Rondo and was all over Nelson, an All-Star point guard the previous season, like white on rice. I’ve never seen defense like this from start to finish of a game. Ever. It truly was inspiring, and the rest of the C’s fed off of it. Avery literally had Nelson begging for mercy, as the then 21-year-old shared after the game.

“He seemed like he didn’t even want to bring the ball up,” Avery said that night with a little extra zest. “I looked at him and he kept telling me throughout the game, ‘Don’t pick me up! Don’t pick me up!’ And that’s when I knew if I brought pressure, he didn’t want nothing to do with it.”

Bradley began to make a similar defensive impact on a nightly basis, and he began to hit his 3s, too. He eventually stole the starting shooting guard role from Allen, a future Hall-of-Famer, during March of his second season.

But in the midst of the 2012 playoffs, Avery’s shoulders gave out – quite literally. He played through the pain while he could, as team medical personnel continued to pop his shoulders back into place, but it eventually reached a point where the C’s could no longer allow him to take the court. He missed the final three games of the Eastern Conference Semifinals, and all seven games of the Eastern Conference Finals against LeBron James, Dwyane Wade and the Miami Heat.

It wasn’t long too after that that Avery would suffer the greatest loss of his life. His mother, Alicia Jones-Bradley, passed away in September of 2013. Avery rightfully struggled mightily to cope with the loss during the following years.

Whenever you see him hit a 3-pointer and point to the sky, that’s who he’s pointing to. She meant and still means the world to him.

What would soon bring him back was a moment at the opposite end of the spectrum, when he witnessed the birth of his first child, Avery Bradley III, just two weeks later. Avery would go on to marry his beautiful wife, Ashley, welcome another child, Ashton, and the couple will soon welcome the birth of their first daughter.

All the while, Avery continued to improve each and every season. I’ll never forget Doc talking about DeMar DeRozan back in the day, and raving about how he knew DeRozan would become a great player because he improved every single year.

That’s Avery. Avery has gotten better literally every single year of his career. He just posted career highs in points, rebounds and assists. I’ll expect nothing less from him as he now joins the Pistons.

Detroit is getting a rock-solid player, but it’s getting an even better person. That shy, quiet 19-year-old is no longer around – OK, he might still be quiet, but Avery is such a different person.

Avery is a leader. He’s a model citizen. He’s a proud father and husband. He’s a true asset to a community. And, least importantly, he’s a pretty darn good basketball player, too.

I watched Avery come in back in 2010 as a timid youngster who faced dramatic challenges, but it was so rewarding to watch him battle through those roadblocks and become the man and player he is today, all while building a long-lasting relationship.

That’s why today is so tough. It’s always difficult to say goodbye, but it’s really difficult to say goodbye to one of the best people you’ve ever met, and a person for whom you hold so much respect.

Detroit, Boston’s loss is your gain, in so many ways. I hope you enjoy your time with Avery as much as I did.