Danny Ainge, president of basketball operations of NBA's Boston Celtics, has resigned from his position and the team's head coach Brad Stevens will take over, the team announced on Wednesday.

"It was my decision. I don't know if there was a moment in time, but like I said earlier, I trust my instincts, and my instincts told me a couple of months ago that it was time for me to move on, and that's what's best for us, that's what's best for the Celtics," said Ainge at a press conference on Wednesday.

The Celtics were eliminated by the Brooklyn Nets 4-1 in the first-round series. Though the team fought hard with a broken squad and witnessed remarkable growth of their ace Jayson Tatum, many blamed Ainge for the elimination.

Some of the criticism is called for because Ainge missed multiple opportunities to bring star players to TD Garden – Jimmy Butler, Victor Oladipo, James Harden. Moreover, some of the deals he made in recent years did not help the team as they had expected. For example, trading to acquire Kemba Walker, signing Tristan Thompson, introducing Evan Fournier – the list goes on.

However, to be fair, Ainge is the reason that the Celtics can afford to make the aforementioned mistakes while remaining competitive in the Eastern Conference. Ainge has been behind every key moment of the team in the past 18 years.

Ainge, who won two NBA Championships with the Celtics as a player in the 1980s, was hired as the team's executive director of basketball operations in 2003. It did not take him long to earn the nickname "Trader Ainge" – he sent three-time All-Star forward Antoine Walker to the Dallas Mavericks in the first year.

The league saw Ainge's power for the first time in the summer of 2007. The Celtics finished the previous season with a 24-58 record, the second worst in the franchise's history. When their ace Paul Pierce was upset enough to request a trade, Ainge made his move. First he traded Delonte West, Wally Szczerbiak and the fifth overall pick in the 2007 NBA Draft, which turned out to be Jeff Green, for Ray Allen from the Seattle Seahawks. Then Ainge sent Al Jefferson, Ryan Gomes, Sebastian Telfair, Gerald Green, Theo Ratliff, cash considerations and two first-rounders for 2009 to the Minnesota Timberwolves for Kevin Garnett.

Ainge bet over half of the team's assets on the Big Three that averaged 31 years old, not to mention that none of them ever appeared in the NBA Finals before.

In the following 2007-08 season, the Celtics were 66-16 in the regular season and beat the Los Angeles Lakers 4-2 in the finals to win their 17th title in the franchise's history. The team continued to remain competitive until 2013 when Ainge made more bold and cold deals.

In 2013 summer, the Celtics' Garnett, Pierce and Terry were sent to the Brooklyn Nets for a bunch of role players and, so much more importantly, first rounders for 2014, 2016 and 2018 as well as draft pick swap for 2017.

Back then, many thought it would take the Celtics years to rebuild. Nonetheless, the team only missed the playoffs once in 2014. They even made the Eastern Finals three times in 2017, 2018 and 2020. During the same time, Ainge turned the draft picks he earned from the Nets into Jaylen Brown (2016) and Jayson Tatum (2017). He landed Kyrie Irving from the Cleveland Cavaliers in a trade based on the 2018 first-rounder from the Nets, though the cooperation between Irving and the Celtics did not work well.

Ainge revealed that he began to consider retiring after suffering a heart attack in 2019. Moreover, the COVID-19 pandemic made the recent years very tough. "In the bubble and all the rules and scrutiny and protocols that we had to go through has not made the job as much fun," said the 62-year-old.

"I'm excited for Brad. He was born for this," said Ainge.

Steven started his NBA coaching career in 2013 with the Celtics and he has been with the team all the time.

"I'm passionate about this group of people, I'm passionate about the team we have, I'm passionate about the people that work in our front office, I'm passionate about our coaching staff, and that's who I've spent all morning with. I do think I have a good insight into our team as Danny now steps away," said Stevens.

Celtics owner Wyc Grousbeck said Stevens agreed to "win banner 18 or die trying."

Though the transition now seems so warm and nice, what awaits Stevens and the Celtics is no picnic. The team will have a clear young star basis of Brown and Tatum thanks to the multi-year contract extensions they signed, but so will Walker. The 31-year-old still has two years left of his contract worth $76 million. According to ESPN's expert Bobby Marks, the team will enter the offseason with a total salary of $130 million, which is worryingly close to the luxury line of $136 million.

That is only the number before they take care of contract extension issues. Fournier will become a free agent this summer and his salary this season is $17 million. Even if the Celtics convince him to accept a new contract with a starting salary of $10 million, it will result in $19 million of tax.

There is also Marcus Smart, who can resign a four-year, $74.4-million contract in the offseason. The Celtics may have to hesitate for a while over whether they want to keep Smart or trade him. However, they won't when it comes to Thompson's $9.7 million-contract given his disappointing performance this season.

Even if the Celtics somehow handle all these problems, they will remain the same, not better. Moreover, they will find it extremely hard to find quality big men, which is what they need the most. The Celtics have a $5.9 million exception they can use, but not only it's far from enough to sign a good big guy, using the exception will further raise the luxury tax to $35 million.

Things did not start easy for Ainge 18 years ago, and they won't for Stevens.