In 17 games with the Red Claws, Tacko Fall is averaging 10.1 rebounds, 13.5 points and 2.7 blocks in just under 23 minutes per game. He’s shooting 72.7 percent from the field. Brianna Soukup/Staff Photographer

The G League basketball season is more than halfway over, and Tacko Fall has made an obvious impact in terms of excitement and attention.

The Maine Red Claws have sold out 10 of 12 home games at the Portland Expo, and no tickets are available for games against Westchester on Friday and Greensboro on Saturday. Despite appearing in only four NBA games with the Boston Celtics so far, the 7-foot-5 rookie center from Senegal received more All-Star fan votes than stars such as Boston’s Jaylen Brown and Philadelphia’s Ben Simmons.

Some fans even asked for refunds when they showed up for a Red Claws game only to learn the Celtics had summoned Fall, 24, as insurance for their injury-riddled frontcourt.

Of course, for a player on a two-way contract, there’s no way of knowing where he’ll be on a given night. Fall has suited up 10 times for the Celtics and 17 for the Claws, who are 8-0 at the Expo and 14-3 overall with him in the lineup.

The more difficult question: How is Tacko Fall progressing as a basketball player? Will he become a mainstay in the NBA, or is there a defensible reason why all 30 teams passed on him in the draft?

“I feel like I’m on the right track,” he said Thursday after his first practice with the Red Claws since returning from a three-game road trip with the Celtics that included stops in Orlando, New Orleans and Miami, but no game action. “My touch around the basket is a lot better. Coming out of college, I was already a pretty good defender.”

The professional game, of course, has a three-second rule on defense that required an adjustment. Fall can’t simply camp out in the paint with arms spread wide. Defending plenty more pick-and-roll plays is another challenge.

Darren Erman, head coach of the Red Claws, said Fall has improved considerably in that latter category.

“He can play the ball handler and the roller,” Erman said. “With his size and length and being a massive human being, if he becomes elite at it, which I feel like he will be, then he has a long NBA career ahead of him.”

As a screen setter, Fall has reduced his lag time on rolling to the basket, thus putting more pressure on opposing defenses, Erman said. If a defense doesn’t collapse toward the basket, Fall can pull in a lob for an easy basket. If a defense tries to take away the lob, 3-point shots on the weak side become available.

“But if you don’t get out quickly,” Erman said of Fall’s transition from screen setter to potential pass catcher, “then it’s a lot easier for the defense to stay home and his man can get back to him.”

With the Red Claws, Fall is averaging 10.1 rebounds, 13.5 points and 2.7 blocks in just under 23 minutes per game. Among the analytics used in pro basketball is something called the Player Impact Estimate, which tries to measure a player’s overall statistical contribution against the total statistics of games in which they play.

Fall’s PIE is 19.3 percent. That’s not only highest among all Red Claws, but second in the entire G League for players with at least 10 games.

Salt Lake City’s Isaac Haas battles Tacko Fall for a loose ball during a game at the Portland Expo earlier this season. Fall leads the Red Claws in a category called Player Impact Estimate, which measures a player’s overall statistical contribution against the total statistics of a game. Shawn Patrick Ouellette/Staff Photographer Buy this Photo

“It’s fair to say he has a high impact,” Erman said. “If you’re No. 1 in PIE, it doesn’t necessarily mean you’re the best (player), but you’re probably impacting the game at a high level.”

If you’re wondering, the Red Claws player with the second-best PIE is Trey Davis, at 13.8 percent. Maine’s other two-way player, point guard Tremont Waters, checks in at 12.1.

Remy Colfield, a Celtics college scout and general manager of the Red Claws, said one of the major goals was to get Fall comfortable with the faster speed of the professional game. The Celtics have used up 12 of Fall’s 45 allowable NBA days according to the terms of his two-way contract. He concentrates on individual work with coaches when he’s with Boston, because playing and practice time is limited.

“I think he’s doing a fantastic job,” Colfield said. “He’s gaining some knowledge from the NBA squad and bringing what he’s learned down to the G League.”

Of Fall’s 17 points with the Celtics, 10 have come on dunks, two on an alley-oop layup and four on hook shots. Erman can remember only one shot beyond 10 feet with the Red Claws, a 12-foot fadeaway.

Then again, if you’re able to touch the rim without jumping, it makes sense to shoot from close range. Fall is shooting at a 72.7 percent clip.

At the free-throw line, however, he succeeds less than half the time, 46 percent, which is still three points better than he shot in college. Tacko said he made a breakthrough Wednesday while working with Celtics assistant Jay Larranaga.

“My left hand was too involved with my shot,” Fall said. “We kept working at it and I found a good form to shoot with. Now it’s just repetition.”

Scott Morrison, the former Red Claws head coach and current Celtics assistant, guided Boston’s Las Vegas summer league team when Tackomania began to bloom. Morrison said he has seen substantial progress in Fall’s durability, mobility and skill set.

What hasn’t changed, Morrison said, is Fall’s joyful and positive outlook.

“I think everyone is excited when he comes in the room,” Morrison said. “He makes sure he says hi to everyone, gives everyone a high-five, or in his case, a low-five. He’s always smiling, always in a good mood. It’s great for the team.”

If being snubbed in the draft made Fall question whether he could make it in the NBA, his experience so far with the Red Claws and the Celtics has been reassuring.

“Even now, I’m the biggest guy in the NBA, so it’s not a matter of size,” he said. “As long as I go out there and give it 100 percent, I’m pretty sure I can hold my own.”