Now it is mid-October, and the water is turning colder and boats are being put away and the Celtics’ season is beginning. And Zarren chuckles when he realizes that he and his father went sailing just once.

Each offseason, Celtics assistant general manager Mike Zarren sets aside time to go sailing in Marblehead Harbor with his father. This spring the two circled 15 possible dates between June and October, aware that it was an ambitious number given the ever-changing basketball team Zarren helps oversee. But they would try.

“It’s just been the busiest summer that we’ve ever had,” he said.


The Celtics knew there would be change. But no one in their front office envisioned an offseason like this one, when a wrecking ball was let loose on a 53-win team.

They received the No. 1 overall draft pick and then traded it. They reached an agreement with the summer’s marquee free agent on a nerve-racking July 4. They completed a seismic trade that brought a superstar to Boston and sent a beloved and crushed one away, causing at least one team staffer to shed tears despite his enthusiasm about Kyrie Irving’s arrival.

Some of the alterations were difficult, but they were deemed necessary.

“I want to get back to the top, and I didn’t see the upside in our team that I wanted,” co-owner Wyc Grousbeck said. “So I authorized [president of basketball operations Danny Ainge] to go make changes, and we made them.”

In interviews with the Globe, the team’s lead decision-makers offered a behind-the-scenes glimpse at how it all unfolded.

TAKE YOUR PICK

The Celtics would once again receive the Nets’ first-round draft pick, and the Nets were once again a bad basketball team. They finished with the worst record in the NBA.


On May 16, Celtics co-owner Steve Pagliuca was sequestered in the draft lottery room in New York, and he was anxious. When the accounting firm Ernst & Young came in to oversee the drawing, Pagliuca smiled at them and said “La La Land,” a joke about the Best Picture mix-up at the Oscars three months earlier that had been caused by a different firm’s error.

“That didn’t go over well,” Pagliuca said. “I was trying to lighten the mood.”

The Celtics were awarded the top pick and Pagliuca let out a small cheer. In the studio upstairs later, Grousbeck stood in front of the cameras and barely flinched when the results were announced live on national television. He celebrated at dinner in Manhattan with his wife and stepchildren, and never envisioned what would come next.

“We certainly weren’t actively making calls about trading the pick, but teams did reach out to us, just like we would have done,” said Zarren. “I don’t think there’s a year I haven’t called the team that had the No. 1 pick and tried to acquire it. Usually, it’s a very quick conversation.”

One of the early calls came from the 76ers, who had the No. 3 overall choice. Boston and Philadelphia talked off and on for a couple of weeks and eventually had the framework for a deal.

Boston would receive the No. 3 pick, and either the 2018 choice Philadelphia had previously acquired from the Lakers or the 2019 pick the 76ers had acquired from the Kings. Suddenly, in the midst of regular draft prep, the Celtics’ scouting department had to dive into evaluations of top 2018 and 2019 prospects to help place a value on the 76ers’ offer.


But talks stalled when the sides were negotiating conditions on the picks.

“There was a time we thought we wouldn’t do it, because they weren’t willing to give an unprotected pick,” Ainge said. “We were seeing if we could find something better.”

Ultimately, the teams agreed to parameters. Boston would get the Lakers’ choice if it fell between picks 2-5 next year, or the better of the Kings’ and 76ers’ picks in 2019, unless it was No. 1 overall.

The Celtics had become enamored with Duke forward Jayson Tatum. He wowed them during a workout in Los Angeles, and then fell to them at No. 3, just as planned. It was a smooth start to the summer.

Boston used the No. 3 pick in Thursday’s draft to bolster its frontcourt with the forward from Duke. Share Email to a Friend Embed Boston used the No. 3 pick in Thursday’s draft to bolster its frontcourt with the forward from Duke.

CHASING HAYWARD

The Celtics had identified All-Star free agent Gordon Hayward as their focus of this offseason months earlier. But they figured there would be a long line of suitors.

“We were excited when we found out he was just meeting with us, the Jazz, and the Heat,” Ainge said. “That was really good news, because we thought that maybe he would consider LA or San Antonio or some other really good teams. I thought, ‘Well, we’re one of three teams, so we’ve got to put on a good show.’ ”

Last year the Celtics flew a group of nine people, including Patriots quarterback Tom Brady, to the Hamptons to woo free agent Kevin Durant. They tried to put on a good show then. With Hayward, they just turned to head coach Brad Stevens, who had coached him at Butler University and knew him better than most.


Stevens insisted that a simple courtship would be most effective. As other staffers prepared for the draft, Stevens and the analytics group spent weeks crafting a presentation that would highlight how the Celtics would utilize Hayward. The All-Star averaged 21.9 points per game for the Jazz last season, and Utah was the league’s slowest-paced team. With more speed and possessions, Boston envisioned possibility.

Yes, they took Hayward to Fenway Park, where he watched a video highlighting the city’s sports history, but Hayward — an excellent tennis player — might have been even more impressed when Ainge inadvertently drove him past the Longwood Cricket Club, which is known for its immaculate grass courts.

The Celtics were confident in their presentation but unsure of their standing. After Hayward met with the Jazz the following day, Stevens called and asked if he had any new questions.

“If you need me,” Stevens said, “you know how to get ahold of me.”

On July 4, Ainge was at the Utah home of his son Tanner, and Zarren was in his Salt Lake City hotel room working on other deals. The Celtics were playing in the Utah Jazz Summer League and it was their only off day, so Stevens and some other staffers took their children zip-lining in nearby Park City.


That morning, ESPN reported that Hayward had chosen Boston. But Hayward’s agent, Mark Bartelstein, publicly and forcefully denied that a decision had been made, and he told Ainge the same thing.

Internally, the Celtics were concerned that the backlash in Utah from the Hayward report could give him cold feet, or that it could cause the Jazz or Heat to make one last push. Stevens sent Hayward a short text message to check in. Finally, at 7:48 p.m., Hayward posted on the Players’ Tribune that he was bound for Boston.

Danny Ainge confirms signing Gordon Hayward. Share Email to a Friend Embed Danny Ainge confirms signing Gordon Hayward.

THE THREE BUSIEST DAYS

The Celtics had worked for over a year to ensure they would have enough space to make a max-salary offer without breaking up their core. Last summer, the projected cap for this year hovered around $108 million, and Boston initially left about $6 million in wiggle room in case the figure dropped.

But the projection gradually dipped to $103 million in December and $101 million in April before finally settling at $99 million. In order to sign Hayward, Boston would have to shed considerable salary elsewhere, and there was urgency.

“Those were the three busiest days of phone calls,” Zarren said. “I’ve never had a set of days like that. I was basically in my hotel room or Danny’s hotel room from 6 a.m. Utah time — because the Eastern teams would start calling at 8:30 — until about 2 a.m. Utah time, when the Pacific teams were done talking to us.”

Zarren was often on the phone with one team while others beeped in. He filled two hotel notepads scribbling callback lists and potential offers.

The Celtics had spoken to the Pistons early in the process, but a deal seemed unlikely. Late on July 6, Boston had narrowed its choices down to two other deals. Then Detroit called back around midnight.

“They said, ‘You know that thing we talked about earlier in the week? Is that something you’d still have interest in?’ ” said Zarren.

The Celtics did not want to trade Avery Bradley, but they had been enamored with Marcus Morris ever since the 2011 draft. And now he had become even more intriguing, because he had a manageable contract and they believed he defended LeBron James better than most.

After about two hours of negotiations, Boston agreed to send Bradley and his $8 million salary to Detroit for Morris, who makes $5 million, allowing the Celtics to sign Hayward.

“Leaving summer league in Vegas, I think we all thought, ‘Yeah, this is our team,’ ” Zarren said. “And we felt pretty good about it.”

‘HEY, IS THIS REAL?’

Stevens takes a two-week vacation after summer league each year, although it is a bit of a busman’s holiday. He gets up before his children each morning and jots down basketball thoughts and concepts. This offseason had been hectic, but it seemed there was now clarity.

“It’s always my peaceful time of the year, and I had a pretty good feel for what we were going to try to do,” he said. “Then, it got blown up.”

When it was reported in late July that Kyrie Irving had requested to be traded from Cleveland, it was news to the Celtics. Zarren contacted Cleveland general manager Koby Altman, who was just taking over that post for the ousted David Griffin.

“I know Koby pretty well, so I called and said, ‘Hey, is this real?’ ” Zarren said. “And he said he didn’t think everything that was reported was right, but that they might look into moving Kyrie if the right trade came along, but that it would depend on the situation. And, also, they probably didn’t want to trade him to us. He said that right away.”

But the door was not shut, and the two sides maintained a rolling dialogue over several weeks.

The Celtics understood that a deal for Irving would have to include their own All-Star, Isaiah Thomas. Thomas had sacrificed so much for the organization so recently, playing despite the death of his sister, despite needing major dental surgery, and despite tearing a labrum in his hip. But the hip would now complicate matters.

Ainge said the Celtics had received encouraging news after Thomas underwent scans in July. He would continue his regimen of rest and rehab, and have another round of imaging in early September that would offer a clear timetable. But talks with the Cavs were intensifying.

“Obviously there was a lot more discussion about [Thomas’s health] when the trade got closer,” Ainge said, “and now you had both teams looking more closely at everything.”

At some point the Cavaliers were encouraged enough by Thomas’s prognosis to agree to a deal that would send Thomas, Jae Crowder, Ante Zizic, and the 2018 first-round pick Boston would receive from the Nets to Cleveland for Irving. The deal was pending physical exams for all players involved.

When Irving flew to Boston for his physical he met with team staffers and had dinner at the Four Seasons with Ainge and Grousbeck. Grousbeck, who had signed off on the trade despite a fondness for Thomas, was rapt as Irving talked about everything from Ainge’s playing days to Stevens’s coaching acumen. He believed the young point guard would be a perfect fit.

But something during the evaluation of Thomas’s hip gave Cleveland pause, and days passed without the trade being finalized. There were multiple reports that the Cavaliers believed Thomas was more injured than the Celtics had led them to believe, and there was also a belief that the Cavaliers were playing hardball in order to poach another asset from Boston.

“There were certainly a number of times both before and after the first trade call where we didn’t think it was going to happen,” Zarren said.

Eventually, the Celtics became weary.

“We’d waited so long,” Ainge said. “We were OK if it didn’t go through. Obviously that’s tough, because being traded is an emotional time for players. But we obviously liked Isaiah, Jae, and Ante. That would have been fine by us [if the trade was rescinded]. It might not have been fine by Isaiah or Jae, but we liked those guys.”

In the end, the Celtics agreed to add a 2020 second-round pick to finalize the deal. The Celtics and Cavaliers have declined to publicly discuss specifics of that uncomfortable week that followed the initial agreement, and according to a league source, the NBA instructed both sides to keep quiet about it. In the end, though, both sides were relieved that it was over.

Finally, Stevens had the group he could move forward with. It looked nothing like the group he once expected to have, but it was still full of talent and possibility.

“I like the whole idea of building a team,” Stevens said. “I like the whole idea of putting puzzles together.”

All-Star guard Kyrie Irving thinks landing with the Celtics was meant to be. Share Email to a Friend Embed All-Star guard Kyrie Irving thinks landing with the Celtics was meant to be.

Adam Himmelsbach can be reached at adam.himmelsbach@globe.com. Follow him on Twitter @adamhimmelsbach.