As a head coach in a professional sports league, Steve Nash makes perfect sense in Brooklyn the way, say, Jason Garrett once made perfect sense in Dallas.

Garrett was an Ivy League-educated quarterback, the son of a coach, and a longtime NFL backup who, everyone seemed to agree, made “the room” smarter. Bingo, let’s let him run America’s Team.

Nash was a Hall of Famer at his sport’s quarterback position, a fast-breaking orchestra conductor who set up offenses and broke down defenses with relative ease. Bingo, let’s give him a whistle, a whiteboard, and the services of two all-world talents.

Though Garrett had something Nash did not at the time of his big promotion — some meaningful experience as an assistant — he was, like Nash, a pleasant man who, on many nights, appeared to have some talk-radio fan contest to coach the team of your dreams, coming across as a witness more than a participant.

Garrett survived in that mode for 9 ¹/₂ seasons, but it sure doesn’t look like Nash is going to be that lucky with the Nets. In fact, if Brooklyn gets bum-rushed out of the first round of the playoffs by Boston, even Kevin Durant’s imprimatur might not be enough to buy the second-year coach a third season — assuming Durant is still a believer.

The biggest mismatch of the NBA postseason so far is Nash versus his former Nets assistant, Ime Udoka, the rookie head coach of the Celtics and a man who learned the trade under Gregg Popovich. Udoka has absolutely run a defensive clinic in these first two games. The last time a Boston-area coach has unnerved a franchise player the way Udoka has unnerved Durant, Bill Belichick was throwing the kitchen and bathroom sink at Peyton Manning in the early 2000s.

After the Celtics turned a 17-point Game 2 deficit into a seven-point victory and a 2-0 series lead Wednesday night, Durant said it was on him to figure out how to score against the relentless wave of long and active bodies Boston is throwing at him. Kyrie Irving said it was on him, as the point guard, to help make the game easier for his teammate.

Though it was good to hear that accountability is expressed from the most important players, it’s the head coach’s responsibility to put them in a position to succeed. Nash said he wanted to study the tape and “try to help these guys, try to help them improve and give them new ways to attack.” Of course, he should have found a way to help his guys in the second half, long before he boarded the bus.

He also should have spent part of his postgame news conference fighting for Durant and against the way he’s being defended. Refs usually give superstars the benefit of the doubt when opponents are treating them like tackling dummies, and yes, Durant did take 20 free throws in Game 2. But there’s no way Phil Jackson or Pat Riley or (name your great coach) would have watched the Celtics grab and push one of their centerpiece players for two games without campaigning for more whistles in front of the cameras and microphones.

Nash did say in that news conference that his team’s intensity dropped off in the second half, which was an indictment of his own work. How in the world can a team trailing in a playoff series lose intensity — while holding a double-digit lead — in one of the more hostile environments in the league? And one other question:

How can Nash possibly justify his lack of in-game adjustments by saying there is no guarantee that a prospective tweak would’ve worked any better than the strategy that was already failing? Good heavens.

It’s clear that Udoka has what Irving called “the keys to the treasure chest” when it comes to attacking his former team. He does have institutional knowledge about the Nets that Nash doesn’t have about the Celtics, but that is a lame excuse for the way this series has gone down. Nash has more head-coaching experience, and he has on his side one of the 15 greatest players of all time, and one of the most dynamic point guards the sport has seen. That should be enough for a 1-1 series heading into Saturday night’s Game 3 in Barclays Center.

But Nash has Durant and Irving in an 0-2 hole instead. Kenny Atkinson, the man Nash replaced, would have had this series at 1-1. Udoka would have had this series at 2-0 for the Nets, just like he does for the Celtics.

In the fall of 2020, on the same KD podcast that Irving famously said of Nash, “I don’t really see us having a head coach,” Irving also said of him, “You understand why he can coexist with us. Because we don’t need somebody to come in and put their coaching philosophy on everything that we’re doing and change up the wheel.”

It’s now officially time for Steve Nash to change up the wheel. You don’t have to be a great strategist and a great motivator to be a great NBA head coach, but you have to be one or the other. The masterful point guard has to finally pick a path to the goal, or else.