Wyc Grousbeck’s co-ownership of the Celtics turns 17 in December, and he’s signed checks for a wild array of personalities.

Vin Baker, Jim O’Brien, Ricky Davis and Antoine Walker have swirled through the generational blender. Jordan Crawford. Rajon Rondo. P.J. Brown. Doc Rivers. Khris Humphries. Shaquille O’Neal and Rasheed Wallace. The second Big Three.

And the 2008 NBA championship. The hollow feeling from the season before that title, when Paul Pierce was shelved by injury and Rondo was a rookie, tugs at Grousbeck now. He admittedly hasn’t slept well since the Celtics lost four straight games to Milwaukee in the conference semifinals last month.

His dreams weren’t peaceful 12 springs ago, either.

“This is the most uncertain offseason since 2007,” Grousbeck recently said during lunch in the Celtics’ Causeway Street board room.

Though Kyrie Irving’s decision to not exercise the option on the last year of his contract last Wednesday was expected, it also expedited something apocalyptic for the Celtics as we know them. Irving fired longtime agent Jeff Wechsler and, according to an ESPN report, planned to take up with Jay-Z’s ROC Nation Sports. The hip hop icon, of course, was a minor investor in the Brooklyn Nets before selling his stake in 2013, when he got into the business of representing athletes like Kevin Durant and Danny Green.

It’s as if someone put neon paint on all signs to Brooklyn.

Grousbeck tries to balance these troubling developments, and older evidence that Irving never meshed with Brad Stevens’ plan, with what he saw personally following the Celtics’ Game 5 elimination in Milwaukee.

Before going out to say the same during his last press conference, Stevens told his players that he did a bad job.

“Kyrie said, No you didn’t, coach,” recalled Grousbeck, who prefers not to discuss his view on Irving and whatever the all-star guard is thinking. Asked if he has directly asked Irving to come back, the Celtics co-owner said, “I haven’t talked to Kyrie in those terms, and our two free agent negotiators are Brad and Danny (Ainge). But Kyrie knows how we feel about him, that we feel very positive about him, and the discussions will go on over the next few weeks.”

The tortured process of convincing a star player to stay takes Grousbeck back to 2007, too.

“Right down there,” he said, pointing down a hallway to his office. “A meeting with Paul in my office right here, with Danny and Steve Pagliuca, and saying please stay. We’re going to try and get better this summer. But if Paul had left, then what did we have?

“He said I believe, I’ll stay. He wasn’t a free agent, but he had to re-commit and not demand a trade, and we just wanted him to stay,” said Grousbeck. “Ever since then, the summers have been, because the team got better, let’s keep that running as long as we can. Then Doc left and Brad came in, and it was very clearly a build, but none of that had this. We have five or six major choices to make this summer, the most we’ve had for many years.”

Should Irving leave, and the team’s bid for an Anthony Davis trade fall through, then short of moving ahead with what’s left, Danny Ainge’s creativity will be tested like never before. Though he wouldn’t share specifics, Grousbeck has admittedly heard some fairly exotic scenarios being discussed.

“There’s definitely scenarios being spun inside the basketball office,” he said. “I’m there every day listening to them, that involve a number of players. I’ve heard a lot of scenarios. We’ll just see what happens.”

In the meantime, there’s the stuff that still keeps him up nights — disappointment generated by a team that was expected to be so much more. Grousbeck was baited as much as everyone else by the Celtics’ blowout win over Milwaukee in Game 1, before that tease’s painful letdown. The Celtics’ worst regular season traits came to bear.

“We had free agents who wanted minutes, and players who wanted to be All-Stars,” said Grousbeck. “I don’t know. There was a lot of I want this, I want that, I guess. I’m not in the huddles or the locker room on a daily basis, but it’s frustrating.”

Asked if frustration gave way to anger, he said, “I’ve been frustrated and disappointed. I’ve said that it was hard to love this team. But anger’s not going to get me anywhere. Usually when I get angry I get angry at myself. I look at it as, what could I have done better. I usually take that approach. I feel a huge responsibility to put a better team out there. I will not be happy, I will not have a better sleep until we are better. I don’t know if we can do it this summer or not, but that’s all I’m thinking about.”

For now, there’s a curdling lesson that was never more striking than it is now.

“The talent on paper wasn’t translated into winning basketball,” said Grousbeck. “We had a roster that had gotten healthy and had enough talent to do better. I don’t know what went wrong, but there was a disconnect somehow. But I don’t have individual players to blame, and I absolutely do not blame the coach, Brad. He’s top shelf, top coach, exactly who we want coaching the team. But somehow the chemistry was not there. Every fan, of which I’m one, knows the chemistry wasn’t there. We all know that.

“We thought we were getting a better team back,” he said. “Maddening is a word for it. I’ve used frustrating, disappointing. But now is the time of year that is many times my favorite time of the year, because you’re building a new house, casting a new movie. We have so many options this summer, that I really don’t know what will happen over the next two to three weeks. That’s the fun of it, and the stress of it.”

And the mystery of it, too. Ainge recently said that he has no regrets about trading for Irving two summers ago. You simply move on to the next deal, said the Celtics president.

“He and I share that outlook and have over the 16 years we’ve worked together,” said Grousbeck. “I don’t have any interest in being mediocre for the next 10 or 15 years. I’d rather go for it, hit the driver, off the fairway, I occasionally do that. Absolutely that Kyrie trade felt like the right thing to do and was the right thing to do. I completely share Danny’s outlook and support it, of looking at options that are aggressive and could lead to a championship. That’s the mindset.”