For much of Terance Mann’s freshman year at a New Hampshire boarding school, his confidence and his mother’s seemed to rise and fall with his shooting percentage.

A longtime college coach, Daynia La-Force knew what turned heads in recruiting. To friends, she fretted that her oldest son’s inconsistent shot might overshadow his other skills and cost him a shot at fulfilling what appeared to be bursting potential.

Charlton Young told both not to worry.

In the two years since Young, then a coach at Georgia Southern, had met La-Force at a coaching convention, he had become convinced of two things. Mann’s jumper could be reclaimed over thousands of repetitions. But the other plays Mann seemed to enjoy most, the kind no one has ever spliced into a YouTube mixtape, were more difficult to teach.

“He’s doing things kids his age are not doing,” La-Force recalled Young once saying. “Charlton saw something in him that I think was very special.”

Mann drove to create shots for others, then sprinted back on defense. He scrapped for blocks and rebounds and took the tough defensive assignments. He was what Young called “high-speed WiFi” — connecting those around him in an instant, making everyone’s lives easier in the process. Mann’s game was all motion, slashes to the rim and close-outs, and no buffering.

The only time he pumped the brakes was hearing his own ceiling.

“I thought he could be a pro,” Young said. “But if he didn’t develop into a pro and he was just a great college player, I knew he was going to own Starbucks or 22 car dealerships. Just had success written all over him.

“So I offered him [a scholarship] as a ninth-grader and you know what he said to me? He goes, ‘Unc,’ — he called me Unc — ‘are you sure?’

“I just hugged him and said ‘Trust me, you’re going to eat some waffles, you’re going to go do some pushups, you’re going to grow enough, an inch and a half or two. You’re going to get a little tougher, and you’re going to be a pro.’ ”

A decade later, now in his second NBA season, Mann has carved out a foothold within the Clippers’ rotation where none was guaranteed by embracing his role as the producer of “dirty-work” plays that Young once persuaded La-Force would be her son’s ticket to the pros. His reinvented jumper cannot be ignored: While cementing his role over the last 13 games, averaging 21 minutes per night, Mann has shot 55% and made six of 13 three-pointers.

He has chased Brooklyn’s James Harden over a screen to deny an unimpeded path to the rim. He has grabbed rebounds and pushed the pace upcourt. After setting up Utah’s Rudy Gobert, a former defensive player of the year, with a glance to the Clippers’ bench, Mann flicked a no-look pass behind him to the opposite corner for a wide-open three-pointer by Amir Coffey. The play caused deja vu for Young, who recalled seeing a pass just like that a decade ago.

“When he got his opportunity, he stepped up,” center Ivica Zubac said. “He’s playing super hard, he’s bringing a lot of energy on the floor, and he’s even guarding the best players out there. He’s just making winning plays. He’s just doing everything right and I love, we love, the way he plays.”

The breakout within new coach Tyronn Lue’s rotation of bench guards has not registered as a complete surprise for the Clippers, whose scout Leo Papile has known Mann since he was a 13-year-old newcomer to Papile’s high-profile Boston Amateur Basketball Club. Executives kept tabs on Mann during four years at Florida State, where his pitch helped land higher-profile recruits such as Dwayne Bacon and Malik Beasley.

“He called Beasley and Bacon and said, ‘Hey, I know y’all one-on-one guys. I just want to win. You guys come to Florida State with us and I’ll do all the dirty work,’ ” said Young, who joined the Seminoles’ staff in 2013. “I thought for a kid to be that young and have that foresight and that maturity and want to win that badly, he’s one of the most amazing kids I’ve ever recruited.

“You lose a game, some dudes pack up and they go to the club; it’s not a big deal. Terance Mann sits in a locker for 45 minutes with a towel over his head. He loves the game because he’s in love with the process.”

Once as a pro, that process was more challenging to stay in love with. He played more with the Clippers’ G League affiliate last season, suffered a hand injury that required surgery in March, and an attempt to convert the 6-foot-5 guard to a point guard didn’t stick. The team brought him to the NBA’s restart last summer, where his action was mostly confined to the practice court.

In high school, Young would counsel Mann not to worry about high scorers who played the game “dyslexic” — the wrong way. Last season, their conversations sometimes carried a similar tenor.

“He would call when he was down his rookie year and I used to tell him stop giving these dudes superpowers that they don’t have,” Young said. “Make them show you. You just like them. They put their drawers on just like you.

“I think it took him about midyear last year before he understood that.”

Said La-Force: “He could have lost confidence in his style of play. But he didn’t.”

Mann hired a private shooting coach in the offseason, but otherwise didn’t attempt to reinvent his game, doubling down on defense, slashing and energy in hopes of competing for time in a bench backcourt featuring Lou Williams, the NBA’s all-time leading bench scorer, former starter Reggie Jackson and Luke Kennard, who received a four-year extension in December.

Mann has since leapfrogged Kennard, who has been held back by a hesitance Mann has not shown.

“Never ever, ever, ever, ever bet against consistent behavior,” Young said. “His consistent behavior is to get better every year.”

Lue can see traces of his own path in Mann’s. More than two decades ago, Lue was a young guard fighting to build trust on a team with championship expectations too. If the Lakers needed him to guard John Stockton, Lue did it.

“He was working hard last year,” Lue said. “This year he’s able to play more free. I think not playing the point guard position and just being a two or a three, he’s able to slash and cut and fill the lanes and offensive rebound — things like that that have really opened his game up for him.”

Things like that always have. It was why, after Mann played 29 minutes against Utah last month, La-Force wasn’t surprised to hear her son’s first comments during their postgame talk.

“Mom,” Mann said. “Did you see that pass I threw to Amir in the corner?”

TONIGHT

AT BOSTON

When: 4:30 PST

On the air: TV: Prime Ticket, TNT; Radio: 570, 1330

Update: The Celtics (17-17) had lost 14 of 22 before beating Indiana on Friday and Washington on Sunday. Boston ranks 12th in net rating, with Jayson Tatum averaging a team-high 25.2 points and Jaylen Brown averaging 25, but Brown is questionable to play because of a sore left knee. Patrick Patterson remains out for the Clippers (24-12) because of personal reasons.