Boston Celtics general manager Danny Ainge understands that breaking hearts and losing trust is pretty much in the job description.

Ainge is the man who traded franchise icons Paul Pierce, Kevin Garnett, and Rajon Rondo to kickstart a wildly successful rebuild, but this summer's blockbuster trade of Kyrie Irving for Isaiah Thomas shook Ainge to his core.

"It was definitely the toughest call I ever had to make," Ainge told Gary Washburn of the Boston Globe.

Thomas became a beloved figure in Boston in just three seasons. Not only was Thomas the team's leading scorer, but the diminutive guard's fearless leadership resonated with the fan base. Thomas powered Boston to its best season in nearly a decade, played through injury, and suited up shortly after his sister was killed in a car crash. He deserved a major payday from the Celtics after playing his whole career on discounted deals, only to have the rug pulled from under him right before his contract year.

Ainge said he understood the impact that trades have on players and the people around them. It's not easy for the players nor those in management. In so many words, Ainge wanted to say that he wasn't heartless in his decisions.

"I have a pretty good understanding how real this all is involving players and their lives and their families and the disruptions and the emotions. I get all that and that's not easy for players and for coaches and for executives that invest a lot into these players."

The Celtics returned only four players from last season's East-topping side. Ainge won the Gordon Hayward sweepstakes and poached a disgruntled Irving from the Cleveland Cavaliers, but lost several key pieces in the process. Aside from Thomas, Boston also lost Avery Bradley and Jae Crowder in addition to trading down from the No. 1 pick.

In the case of the Thomas trade, it was simply a move the Celtics had to make in Ainge's assessment - even with all the hurt feelings that arose from the deal.

"It's not easy for these office people that become great friends with the players,' Ainge said. "There's a reality that I see and that's what makes any sort of trade challenging. But it's just part of the world that we live in, but it's got to be done.

"You've got to do what's best for the franchise. The franchise is bigger than all of us. Bigger than one individual."