Why does Jaylen Brown struggle at the free throw line?

Down 20 to the 76ers in Game 2, the Celtics chipped all the way back on an 18-3 run to erase most of their massive deficit before half. The most miraculous win of their undefeated (at the time) playoff surge at TD Garden was preceded by Kevin Hart howling in laughter over a problem plaguing Jaylen Brown for years.

Brown approached the free throw line to begin the lofty work for Boston over the next 29 minutes.

He subtly bobbed twice as he bent his knees, then set himself in that position raising his elbows above his head. As his wrists flicked at the highest point, the ball grazed the bottom of the net before bouncing off the ground into the hands of the referee Sean Wright.

In his first game back from a hamstring strain, his playoff free throw percentage fell to 50 percent there. It would rise to his mean — 64 percent — by the end of the postseason. A better number, but one Hart himself might be able to pull off if he tried 100 at the line. Brown’s yet to break 70 percent in a season across one year at California and two with the Celtics.

He stared down at his pink low-topped shoes on his way back to the line while Hart taunted on.

“I was thinking about them too much,” he said earlier in the season. “I was in my own head, really. The reality is that it’s a free throw. But you should still treat it like it’s a jump shot almost. It’s a mental thing.”

He converted his next attempt, adding an extra hip thrust in his follow-through as if he was deadlifting. By the time the halftime buzzer sounded Hart’s laughs became the kiss of death that his ice bath skit was on Blake Griffin’s 2018 season. Philly lost the game and the series, Brown’s miss proved inconsequential in the outcome.

Only once has the sheer number missed free throws by Brown — five in a three-point win the Suns took when Tyler Ulis hit at the buzzer in 2017 — actually cost the Celts a game. Yet the minor slip-ups cost his percentage mightily.

83 misses across 233 attempts ranked Brown 22nd in points left on the table at the free throw line. The non-bigs in that group were Brown, James Harden, Brandon Ingram, DeMar DeRozan, Josh Jackson, Andrew Wiggins, LeBron James and Russell Westbrook. Only Jackson, Ingram and Wiggins joined Brown shooting under 70 percent.

Imagine a world where the Victor Oladipo trade never happened. Erase his miraculous rise with the Pacers for one second to highlight the relative leap of Brown took in 2018.

Oladipo’s scoring average increased 43 percent. His steals doubled, as did his free throw attempts. He hit four out of every five. That startling ascension across every category will certainly earn Oladipo the award without much competition from fellow finalists Clint Capela and Spencer Dinwiddie.

Brown’s candidacy, while formidable, won’t draw close. The last second year player to win the award was Monta Ellis 11 years ago, but one crucial stat diminished across Brown‘s statistics. His free throw percentage fell from 68.5 to 64.4 percent.

If he hit the league average of 77 percent, he would have averaged 14.9 points per game as opposed to 14.5. A slight but worthy increase considering the work he committed to take 233 shots at the line. That put him in the top-3, with Kyrie Irving and Jayson Tatum, on the Celtics as well as top-64 in the NBA. His efficiency ranked in the bottom 10 of that group.

He did embark on a stretch through February where he shot 75 percent. Stressing heart rate and breathing, Micah Shrewsberry tried to ease him through the increased workload he faced in all areas with nearly three extra free throws per game.

“There were times where he’s been a little bit rushed early when he’s shooting it,” he said early in March. “I think it’s more of a mental thing, so he takes a slight pause to get his mind off of whatever else was going on before he gets back to the shot.”

Out of the All-Star break, where he flashed his array of skills in the Rising Stars Challenge, he opened a scorching streak of 29-for-31 shooting free throws.

All of this coincided with a banner year for Brown’s three-point stroke. Coming out of college his 29 percent slash at Cal, averaging less than one make per game, the shot stood out as a major concern as he arrived in Boston.

That disappeared as he ripped off 40 percent of his treys in his sophomore season. A quick look at this three reveals the high arc and fluid motion through his bent knees that produced the biggest shot of his NBA career in Utah.

There was no hesitation, everything remained square through his right hand and his shot landed. The mechanics remain consistent for what’s worked as Brown’s become a 46.5 percent shooter from the field in Year Two.

The same was true for a vital make earlier in his basketball career from a spot less successful on the stat sheet to this point. This shot won his high school team a state championship.

While his form almost exactly mirrors the blunder against the 76ers, the hesitation and the bobbing at the knees is not. Brown’s issues may not be of form, skill or capability but rather rhythm and confidence. Last year his percentage at the line fell from 68 percent at home to 61 on the road. Confidence is a factor he speaks about being crucial to his game.

Yet the long term inconsistency he’s shown stepping 15 feet from the rim doesn’t open any immediate ray of hope for a cerebral player other than his strong finish to last regular season and a year of commanding minutes under his belt.

His misses didn’t directly cause any loss; but two in a four-point loss to the Bucks, one in a four-point loss to the Warriors, one in a three-point loss to the Pelicans, one in a one-point loss to the Heat all matter in games decided by few possessions.

“It’s the easiest shot in the world, and I think that’s why a lot of people miss it,” said Brown in March. “It’s kind of ironic.”