Gliding across the court, Matisse Thybulle looks a lot like Zhaire Smith did when he first arrived in Philadelphia: like a kid.

No doubt, the raw materials are there: the lithe frame, the long stride, the knee-tickling arms. But, well, he’s young, and still awaiting that postgraduate five or 10 or 15 pounds that typically comes after a year or so of sports as a full-time job.

Smith? He’s got it, his arms and shoulders and chest swollen with an extra layer of lean muscle that was not there when the Sixers drafted him at No. 16 overall last summer. The transformation of his body is similar to the one we saw with Ben Simmons over his first couple of years. He looks like a man who can take a shoulder, or fight through a screen, or keep a would-be rebounder on his rear. He looks like a man, period.

Of all of the things that still must be decided between now and the arrival of the Celtics on opening night, the most intriguing -- and, potentially, the most consequential -- are the roles of these two first-round draft picks.

While Thybulle is a full two years older than Smith, who had just turned 19 when the Sixers selected him out of Texas Tech, there is no substitute for NBA experience.

Smith did not get a ton of it last year, when a broken foot and an allergic reaction sapped his strength and kept him out of commission until the spring. But in the 111 minutes that he did play, the Sixers saw the kind of player they will be looking for off the bench: a willing defender, an explosive leaper, a shooter who knocked down six of his 16 attempts from three-point range.

“Just a pogo stick,” was how Brett Brown described what he has seen out of Smith over the first three practices of training camp. “Just a bouncy athlete. He had one or two plays today where you’re like, ‘OK.’ Just an incredibly gifted athlete.'"

Thybulle, meanwhile, has flashed the same court coverage and awareness that he showed throughout his collegiate career at Washington. During the small bit of scrimmage that was open to the media on Tuesday, the rookie made a play where he broke up an entry pass and then chased down the loose ball and saved it to a teammate before it bounced out of bounds.

“What he can do is he can cover a mistake as well as any young kid that I have coached,” Brown said. “For instance, if he tries to go steal a ball and misses and somebody back-cuts, he can make up ground, get back in the play, and block the shot.”

At the very least, Smith and Thybulle give the Sixers something to dream on as the regular season approaches.

While Brown has been careful to avoid giving anything away with regard to the projected pecking order on his bench, the odds would suggest that James Ennis will enter the season as the first wing off the bench. That’s the role he played last postseason, when he averaged 21.1 minutes per game, and you would assume the Sixers brought him back for a reason.

With Mike Scott subbing in at the four, Kyle O’Quinn at the five, and either Trey Burke or Raul Neto backing up Simmons at the point, there would not appear to be a ton of minutes available in a rotation that was essentially nine deep at the start of last season.

On Wednesday, Brown included both Smith and Thybulle in a group of young players that also includes Shake Milton and Furkan Korkmaz. The big question is whether one of those players can emerge and push Ennis or one of the point guards for minutes.

One way to do that would be by establishing themselves as capable of matching up against NBA wings while proving to be a more consistent shooter or a more dynamic scorer than the workmanlike Ennis, who shot .306 from three-point range with the Sixers in the regular season and .281 in the postseason.

Smith, for one, expects that his role will be a gritty one.

“Probably just coming in and playing defense, dirty work, doing what I do," the second-year player said Wednesday.

And that sounds good to him?

“Yeah,” he said with a smile.

The competition will start to play out in front of public eyes in Wilmington on Saturday, when the Sixers host their annual intrasquad scrimmage.

Once the regular season starts, Brown will have plenty of options with regard to deploying his bench. These next three weeks will be an opportunity for two first-round picks to force their way toward the top of that list.