Danny Ainge blew up his team. The Celtics were 41-14 when the trade was made. They were the top seed in the East, the most feared team in the NBA, consensus favorites to return to the Finals for the third time in four years. It was going to be the last roundup for the Big Three.

Something happened after the deal went down. The Celtics lost their mojo. They lost their way. While Doc Rivers tried integrating five new players and we all played the absurd “Shaq is coming back this weekend’’ game, the Celtics lost the top seed and the No. 2 seed. Rajon Rondo lost his standing as an elite point guard. Teams such as the Bobcats were suddenly confident playing on the parquet floor.

The Celtics are 14-12 since the deal and have lost 11 of their last 20. They were most recently humiliated by the Bulls and Heat, teams they figure to face if they get past the Knicks in the first round of the playoffs. For the record, the Oklahoma City Thunder are 20-7 since the All-Star break and have a chance to get to the Western Conference finals.

“I think we lost a handful of games in the last 20 that we should not have lost, and that’s not good,’’ acknowledged Ainge, the Celtics president. “Nobody wants that. I don’t think we had the resolve. I wish I knew why we weren’t playing well.’’

Coach Rivers says it’s “too simple’’ to blame it on the deal.

Call me simple. I blame the deal. Something changed. This team lost its toughness. It was the end of Ubuntu. The end of the Big Three Celtics as we knew them.

I’ve heard all the spin. Perkins was not Bill Russell. The Celtics were going to lose him and get nothing in return over the summer. Jeff Green was going to bring youth, scoring, defense, and rebounding to the bench. The Celtics were better with Shaq than with Perkins. The deal was going to make the Celtics better this year.

Baloney. The Celtics have gone into the tank, and the 39-year-old Shaquille O’Neal has played five minutes since Feb. 1 (he limped off with a no-contact calf injury April 3), but now we’re told he’s going to be just fine for the playoffs. He’ll be the first injury-prone, 39-year-old, 400-pound guy to return in game shape after a 2 1/2-month layoff.

Ainge still believes. And he says he’d make the same deal today.

“I think that we’re a better team and set up for the future,’’ he said. “I don’t think the trade has anything to do with why the team is not playing well. It’s easy to sit there and say it’s because of the trade.’’

If the Celtics don’t get out of the East, Ainge is going to get the blame — and not his four All-Star starters who are playing poorly.

“It’s good that the focus is on me,’’ said Ainge. “I just hope the players don’t use that as a crutch. When we made the deal, we were all on board.’’

It bothers me when Ainge says he probably would not have traded Perkins if he’d been able to sign him to a four-year deal that was offered last summer. That means this deal was about the future, not about now. A team with Ray Allen, Paul Pierce, and Kevin Garnett has to play to win now.

Ainge still believes in his team’s chances for 2011.

“I know I was worried about our team last year more than this year,’’ he said. “Paul was hurt and we weren’t able to get KG any rest.

“This year, our big four is healthier than last year and we’ve added some good firepower off the bench, especially with Delonte [West] and Jeff Green. We still have Glen Davis continuing to improve and I’m encouraged by Jermaine O’Neal and how he is physically.’’

What about the pipe dream of Shaquille coming out of mothballs to the rescue?

“I don’t think it’s a dream,’’ said Ainge. “I’m listening to my doctors and Shaquille and our trainer, and they all think he’ll be ready to go. I understand the track record. We all have some doubts about how long he will last because of what happened this year. I get all that.

“Right after the deal, we won five in a row and then we started playing terribly. But do you think the dip in our 3-point shooting and field goal percentage is because of Perk? Perk was not a guy that helped our offense.’’

What’s wrong with Rondo?

“I don’t know. He’s had a couple of really good games. He got some rest. Maybe he’s mentally and physically fatigued.’’

What about the myth of Jeff Green? He hasn’t rebounded or defended the way he was billed. He has had trouble assimilating.

“You don’t think 10 points in 21 minutes a night is productive for our team?’’ countered Ainge.

“Listen, we came in this year and had the best team that we’ve had in my time here for the first 45 games of the season. I believe we can return to that.’’

Not me. Kendrick Perkins isn’t walking through that door. Shaquille O’Neal might be walking through that door, but he’ll probably be limping out the door, and so will the Celtics — somewhere short of the NBA Finals.

Dan Shaughnessy is a Globe columnist. He can be reached at dshaughnessy@globe.com.