As it turns out, Jim O’Brien is the guy who really was Born To Coach.

It was Ricky Pitino, you’ll remember although you might prefer to forget who was supposed to turn around the reeling, struggling, ailing, moribund, once-proud-but-too-long-down-and-out franchise that was the Celtics.

Ricky P. arrived in a blizzard of hype and Paul Gaston’s dollars 7 million of ’em a year and with a reputation as a miracle worker.

He left a year ago January having earned the rep, or, more appropriately, the rap, as The Biggest Flop in the History of Boston Sports.

Great things were expected of Pitino. But it is the quiet, unassuming O’Brien who has gotten the job done, after the much more heralded Pitino quit the job in frustration. It was just 16 months ago that Rick threw up his hands and threw in the towel.

He had taken the team as far as he could, which turned out to be nowhere.

He had drafted poorly, with the obvious exception of Paul Pierce. He made some hasty, and occasionally panicky, trades. And, worst of all, the hyper-intense, total-control, micro-managing style of coaching that had been so effective for him in college clearly wasn’t working in the NBA.

Pitino was supposed to be a master of motivation, but his techniques were a failure with the Celtics, who tuned him out.

They quit on him, and then he quit on them.

Celtics superstars Pierce and Antoine Walker, who chafed under Pitino, have blossomed under O’Brien.

No one in the NBA this year has done a better job of coaching than O’Brien, who has the Celtics in the playoffs for the first time since 1995. Boston is in the conference finals for the first time since 1988.

Meanwhile, Pitino is using his salesmanship techniques to convince AAU stars of the array of academic opportunities awaiting at that bastion of higher learning, the University of Louisville.

Who’d ever have thought it would turn out this way. The highlight of O’Brien’s collegiate coaching career was getting fired at Dayton. Pitino took an overachieving Providence College team to the Final Four in 1987 with one of the truly great coaching jobs of all time, and won a national championship at Kentucky.

But Ricky couldn’t win more than he lost with the Celtics.

And, when he couldn’t take the losing any more, he took a hike.

O’Brien’s personality is better-suited to the pro game than Pitino’s. Thanks to the brilliance of assistant coach Dick Harter, the Celts are playing smothering defense.

It was harassing defense, you may remember, that was supposed to be one of the trademarks of Pitino-coached teams. But the Celtics are playing much better “D” now than they ever did under Ricky P.

Offensively, while the more confident, more polished, Pierce and Walker are the go-to guys, the Celts have other options,as they showed in the fourth quarter of Game Five in Detroit, when they pulled away from the Pistons while the Big Two were on the bench in foul trouble.

A significant part of that improvement has been the addition of Rodney Rogers and Tony Delk.

No Rogers, no Delk, no conference finals. No O’Brien no conference finals.