Tacko Fall, played in only seven games for the Celtics last season, seeing most of his game action with the G League’s Maine Red Claws, but Boston still has hope that he can find a regular role in the NBA. Mark J. Terrill/Associated Press

Boston Celtics assistant coach Jay Larranaga is sort of like a test pilot.

Tacko Fall is his plane.

Seven-and-a-half feet of moldable talent doesn’t come along often in the NBA, and today’s game demands a lot more from tall people than just being tall.

The Celtics, and Larranaga, are determined to figure it out.

“Second half of (last) season, I was in Boston a lot working with Coach Jay Larranaga,” Fall said on Sunday afternoon. “I went through a whole program for strength and conditioning until the season got caught short with the COVID-19.”

Larranaga’s approach has been to pull Fall out of his comfort zone. He has been seen shooting 3-pointers and doing ball-handling drills like a guard. The goal has been to make Fall more comfortable each time he steps further away from the hoop.

Still, his stature is why he’s in the NBA in the first place, and everyone knows that playing Fall means the team has to find ways to use that one thing that differentiates him. The people love seeing him dunk and land while still holding onto the rim, but what good is that if the entire offense bogs down with him in the game?

This is Boston’s challenge with Fall. Can he grasp and execute enough of the uncomfortable stuff for them to be able to take advantage of him where his size matters most?

“He’s such a unique player,” Coach Brad Stevens told reporters. “Our team is generally not a post-up team, just based on the strengths of our other players. And so he does a good job of balancing what some of our other bigs do with doing his strengths, and we all need to recognize that when he’s in the game and try to take advantage of that.”

Fall might seem like a relic of the past when lumbering bigs would be the focal point of team construction. Maybe he’d have a larger role in the halcyon days of 7-footers patrolling the paint. But instead of going extinct like a dinosaur, Fall understands that he has to evolve to fit in the 2020 NBA.

“Coming out of college, pretty much all I would do is run rim to rim and just post up in the block,” Fall said. “Here, we run a lot of actions through the bigs, especially in the free-throw line area. So being able to handle the ball in there, being able to hand it off to the guards coming off screens, and being able to move without the ball was something I had to learn last year. I’ve done a lot of different things, especially with Coach Jay, to be able to help with that.”

Grant Williams, who spent a lot of time with Fall on and off the court and working out together in the offseason, has noticed Fall’s progression.

“He’s just improved in terms of seeing the game a little bit better,” Williams said. “Conditioning, especially, because last year when he got tired, he kind of just let plays go. This year, he’s done a better job of competing every single play, and lastly, he’s just kind of worked on his handle a little bit more. Before, he was a little uncomfortable on the perimeter even going to dribble handoffs, and it’s a credit to him and Jay working all summer, not only just handling, being able to go into actions, keep the ball down and keep his body in between so people can’t reach and go after him.”

The Celtics see a future for Fall in the NBA. They believe he has enough skill to make his size useful. It’s that belief that brought him back to Boston for another year of development.

“The relationships that I’ve built here, whether it’s my teammates, whether it’s with the coaches, I feel very comfortable here,” Fall said. “My game grew a lot because, like I said earlier, I’m in an organization where they believe in me. They took a chance on me last year where a lot of teams had a lot of question marks, but they saw that I had a lot of potential. So you always want to go where you’re wanted. I know I’m wanted here, I know that they are going to help me develop my game, and they are going to utilize me the best possible way.”

Fall admits he’s a work in progress and that he’s nowhere near where he wants to be. In his second year, and back on a two-way contract, Fall is looking to continue his mental growth as a basketball player so it maybe someday matches his physical growth.

“I think he’s improved in every which way,” Stevens said. “He works really hard. I think his body looks great. I feel like he’s in good shape as he’s been. And we’re glad he’s here.”