As the Celtics prepare to meet the Bucks in Sunday’s opener of their conference semifinal series, we welcome you to what has become the annual flogging of Danny Ainge for not picking Giannis Antetokounmpo in the 2013 NBA draft.

The Celt president of basketball operations is certainly not the only one in his profession on the firing line for letting this Mediterranean gem slip through his fingers, but as Antetokounmpo has evolved into an MVP candidate, Ainge is even more willing to take the paddle to himself these days.

“Sure, I mean, I second-guess a lot of guys,” he said. “But, yeah, based on the information I had at the time of the draft, I don’t really second-guess.

“But based on the information from when I first saw him in the summer league, I absolutely started second-guessing,” Ainge added through a chuckle, his eyes widening. “Like, who is that kid right there?”

What’s crazy to recall is just how many moving parts there were for the Celts on that June 2013 draft night. Earlier in the day, they’d reached agreement on the deal to send Paul Pierce and Kevin Garnett to Brooklyn for a truckload of draft picks that would constitute the Big Dig for the club’s reconstruction. Doc Rivers had walked out the door, but Brad Stevens was yet to be hired.

The C’s wanted to pick Kelly Olynyk, so they traded up from 16 to Dallas’ spot at 13. Antetokounmpo, gifted but very raw, went at 15 to Milwaukee.

Now he is viewed as gifted, diligent and — frighteningly — still improving.

“He’s a lot like LeBron in some ways, in that he’s just a good all-around player,” said Ainge. “Shooting may be his biggest weakness, but it doesn’t really matter if he even makes shots; he’s just so effective at still scoring and scoring efficiently and creating offense. And obviously LeBron’s become a very good shooter as his career has moved on, and Giannis is getting better, too. But the fact is that they’re just bigger and more athletic than most everybody they go against, and they have such versatility offensively and defensively.

“One thing I really appreciate about Giannis as a player is his enthusiasm and passion for the game. I think it’s a very underrated characteristic, and I think that he is an inspirational player to his team. His teammates, they really appear to love playing with Giannis.”

The problem with projecting players in the draft is the personnel people can only see what’s in front of them and, with some research into their background and character, guess the rest. Anthony Bennett was the first pick in that 2013 draft. Enough said?

The players who truly excel are those who don’t see getting to the NBA as the finish line. Those like Antetokounmpo (and, we might add, Larry Bird among many others) have the burning need to always get better, to add something to their game. This is why Giannis is an even more formidable opponent for the Celtics than he was in last year’s playoffs.

“This is just my opinion, but I believe that players like to do what they’re really good at,” said Ainge. “Like Ray Allen, he loved to be in the gym shooting, and Mark West, he loved to be in the weight room pumping iron. And I think that Giannis is obviously working hard on the parts of his game that had to improve.

“He has a good-naturedness about him. When he was young, you could see how much joy he had in the game. His motivation to become great got better and better and better as he was getting better. Like he went, wow, and surprised himself. From when I saw him play in Greece in a couple of Division 2 games to where he is now is just mind-boggling and unimaginable. It’s a great credit to him. I mean, obviously he has great physical tools, but he also has an incredible work ethic and joy for the game.”

That tool box had yet to reveal itself when Antetokounmpo was being scouted. He would be a reward only for a team willing to take a chance.

“We all liked him,” Ainge said “All of us had seen him. I think I saw him in maybe January, but by the time that he was drafted that same year, he was I think two or three inches taller and maybe 10 or 15 pounds heavier. And he was even bigger the year after Milwaukee drafted him. But he was just a really skinny kid that had no outside game, and he looked like a kid that just needed a long time to develop.

“I think the amazing thing with him was how quickly he developed, and part of that was his height and strength and how much bigger he got so fast. I think that enabled him to be good right away in the NBA. In his rookie year and his second year, you could see, wow, this kid is going to be really, really good.”

And the fact Antetokounmpo is likely to be even better next year is sure to come up in the 2020 episode of Flogging Danny.