Many Celtics fans wanted drastic changes. Now we’ll see how that works out

Brad Stevens coached 636 regular-season games for the Celtics.John Tlumacki/Globe Staff

Every few seasons during Danny Ainge’s 18-year run as the Celtics’ chief basketball decision-maker, something seismic would occur in the spring or summer.

Sometimes we’d feel the rumblings, know the earthquake was coming. The Kevin Garnett trade in July 2007 percolated for weeks if not months. Same with the Kyrie Irving trade, culminated in August 2017.

The pursuits of coveted free agents Al Horford (July 2016) and Gordon Hayward (July 2017) were packed with suspense before they were consummated.

I can think of just twice when the seismic event came as a total surprise: When Butler University wunderkind Brad Stevens was hired by Ainge to replace Doc Rivers as coach in July 2013.

The second time? You know. You’re still thinking about it and what it means, all these hours after ESPN’s Adrian Wojnarowski rattled the basketball universe Wednesday morning with the news that after eight seasons, three trips to the Eastern Conference Finals, and one lethargic bummer of a 2021 season, Stevens was replacing the man who hired him.

Well, Celtics fans, many of you wanted drastic changes after this disjointed, battered, and frustrating edition went 36-36 in the regular season, won a play-in game they never should have had to play, then were bounced in the first round by all-time front-runner Irving and the loathsome superteam Nets in five games.

And you’ve got ‘em … just not in the way anyone anticipated. I must admit to great amusement that those who wanted the publicly easygoing Stevens gone as Celtics coach indeed got their wish — with the twist that he’s now running the whole operation. What, not quite what you had in mind?

Stevens is a bright basketball mind who presumably will get a rejuvenating jolt from the new role. Say this: There’s no one who knows the Celtics personnel better. We’re going to find out what he really thinks of every single player on this roster.

But it can’t be underestimated that he’s a front-office novice. I suspect he will do well, but there’s no way to know now, and the calculus of roster building is complex and limiting in ways that coaching is not.

There are difficult roster decisions to be made this summer, none more pressing than figuring out how to proceed with Kemba Walker and his oil-leaking knee. The salary-cap situation leaves the Celtics with little wiggle room to enhance a roster that at the very least needs an influx of quality veteran depth to support young stars Jayson Tatum and Jaylen Brown.

Good luck with the rapid repairs, Brad. And you thought getting Marcus Smart to stop jacking threes with 15 seconds on the shot clock was tough.

From left, Celtics co-owner Wyc Grousbeck, former coach Brad Stevens, former president of basketball operations Danny Ainge, and co-owner Steve Pagliuca.Auerbach Center

Call me cautiously intrigued to see how Stevens will proceed. But I’m bummed Ainge is leaving, a departure the Celtics chose to call a retirement even as reports that he might join another organization in a consultant role began circulating before the press release confirming Woj’s report began hitting inboxes. He was very good at an extremely difficult job for a long time, and the most vocal part of the fan base seemed to have little appreciation for him.

Sure, there are regrettable transactions on his ledger. Trading for Irving was the right move, but he ended up poisoning the locker room before quitting and leaving, and signing Walker to replace him has left them hamstrung. It’s lamentable to look at basketball-reference and see Matisse Thybulle and Desmond Bane listed as Celtics draft picks. I’ll never get what he saw in J.R. Giddens, JaJuan Johnson, or Guerschon Yabusele.

You won’t find a general manager in the modern NBA who doesn’t have deals that make him wish for a mulligan. And Ainge’s personnel successes were far more frequent, and often inspired. He built the New Big Three, acquiring Kevin Garnett and Ray Allen to join up with Paul Pierce. That group won one title, and could have had at least two more if not for injuries and the existence of LeBron James. Ainge kept them together a little too long, through the 2012 season, but not a day of it was regrettable.

When he broke up that team, he made an Auerbachian all-timer of a trade, acquiring three unprotected first-round picks from the Nets for essentially Garnett and Pierce. He used two of those picks to choose Tatum (after another savvy deal with the Sixers) and Brown; neither was a consensus choice. Some of you nitwits booed the Brown pick. I’m sorry he didn’t take your guy … who was it? Kris Dunn? Dragan Bender? To think, all of that YouTube scouting gone to waste.

Any notion that Ainge was a poor drafter is laughably devoid of context and truth. Some picks technically came via trades, but Ainge essentially drafted Tatum, Brown, Smart, Rajon Rondo, Kendrick Perkins, Al Jefferson, Terry Rozier, Avery Bradley, Tony Allen, Glen Davis, Leon Powe, Robert Williams III, Delonte West, Jeff Green, and E’Twaun Moore.

Only the first three mentioned and Green, who was traded to Seattle in the Ray Allen deal, went before the No. 16 pick. The picks of the last two years — Romeo Langford, Aaron Nesmith, and Payton Pritchard — all showed promise. The best game of Langford’s career was the most recent one. A normal offseason and summer league should accelerate growth for all three.

What else? Ainge traded for Isaiah Thomas and Jae Crowder, both favorites on overachieving Celtics teams. He acquired Irving, a superstar talent who was supposed to lead the next Celtics champions but instead became afflicted with wanderlust. He signed Horford and Hayward.

I’m not sure how he was supposed to prevent all three from bolting as free agents, the first because of the whims of his ego, the latter two because of offers that exceeded their value. Building those talent-rich 2018 and ’19 teams was a brilliantly executed plan, unfulfilled.

Ainge was remarkably adept at pivoting when a plan didn’t work. The one glaring, reactionary mistake was signing Walker after Irving abandoned ship, and even that looked like a nice alternative plan at the time. (Walker started the All-Star Game his first season here.)

If you’re claiming in retrospect that Ainge should have just kept Rozier, you don’t remember how erratically he played in his final season here. Charlotte was the right spot for him to find his identity in this league.

I’m not sure what else Ainge was supposed to do differently, beyond guessing that Giannis Antetokounmpo, the 15th pick in 2013, would grow 3 inches and develop the skill set of a Marvel superhero. It’s harder to build a contender in the NBA than in any other sport. Having multiple superstars is essential, and you acquire them by tanking for a high lottery pick, being blessed with extraordinary luck, or having the good fortune of a couple of established ones deciding they want to join forces in your city.

Yes, the Celtics won just one championship in Ainge’s 18 seasons. You know how many teams won more than that in that stretch? Four: the Spurs (4), Lakers (3), Heat (3), and Warriors (3). LeBron James, Kevin Durant, and Kawhi Leonard have won eight of the last nine Finals MVPs.

Superstars win, and Ainge did his best again and again to get one here, whether it was by trading for Garnett and later Irving, pursuing Durant as a free agent, or properly identifying the best available player in the draft when it was time to cash in the two highest Nets picks.

Perhaps Tatum, who averaged 40.6 points per game over the final three games of the Nets series, and Brown can be the cornerstones of the next great Celtics team. Their growth hasn’t been linear, but both keep getting better and better. The next step is to solve how to play well off each other. But there will be a new coach in their ear next year, and the person who had the wisdom to draft them is off to the golf course for a well-deserved respite.

Ainge was a beloved Celtic as a player, a member of the greatest starting five in league history. He made a much greater impact as an executive. His No. 44 belongs in the rafters, representing his entire time here, right up there with that 17th banner. It’s the proper appreciation, already overdue.

Now here’s to finding out what his successor, the college whiz Ainge stealthily hired all those years ago, can do.

Ainge: This is a bittersweet day

Danny Ainge spoke with press, along with Brad Stevens, about his retirement as the Celtics’ president of basketball operations.