What does French center Vincent Poirier bring to the Celtics?

Vincent Poirier (with ball) played for the Orlando Magic summer team in 2016.John Raoux/AP/Associated Press

The Celtics on Tuesday continued to solidify their frontcourt, as they re-signed center Daniel Theis and signed French big man Vincent Poirier, according to NBA sources. Also, Boston is bringing back guard Brad Wanamaker on a one-year contract, according to ESPN.

Theis received a two-year, $10 million deal, while Poirier will get a two-year deal. On Monday, Boston agreed to a two-year, $10 million deal with veteran center Enes Kanter. Boston traded center Aron Baynes to the Suns on draft night, and on Sunday forward Al Horford agreed to a four-year deal with the 76ers.

Celtics fans are quite familiar with Theis, who averaged 5.5 points and 3.9 rebounds in a limited role backing up Horford and Baynes over the past two seasons. Theis should be in line for a more substantial workload now that both of those players have departed. Wanamaker played in just 36 games last season and averaged 3.9 points.

But Poirier is much more of an unknown. The 6-foot-11-inch Poirier played for the Magic’s summer league team in 2016 before playing for the Nets’ summer squad in 2017. Last season, he averaged 9.1 points and 6.2 rebounds while making 61.4 percent of his shots for Euroleague power Baskonia.

Celtics forward Guerschon Yabusele, who is also from France, said he has known Poirier for about 10 years. They have faced each other several times, and Yabusele said Poirier’s improvement in recent years has been obvious.

“He got stronger,” Yabusele said. “He has better hands. His confidence is different. He sets the screen and rolls fast to the rim, he has the capability to grab rebounds, and is a good shot blocker. He’s able to finish at the rim strong and all the little things we can use. He played this season in Euroleague and he was playing really good, too. So I know he’s more mature, more prepared, and definitely better. So I really think he can help the team.”

Celtics representatives saw Poirier play in person more than 10 times over the last two years, including when his team matched up in 2018 against the Turkish club Fenerbahce, which then featured Wanamaker.

One league source who is familiar with Poirier’s game said he did not start playing basketball until he was 17 years old, and acknowledged that as recently as four years ago “he was not that good.” But since then he has combined his obvious physical tools with a better understanding of the game, and he has become more of a force.

He is a good rim runner and is active in pick-and-rolls, and he should give the Celtics some of the rim protection they will be losing with the departures of Horford and Baynes.

Poirier is officially listed at 6-11, but in Europe — unlike in the NBA — those heights are usually measured while not wearing shoes. In the US, he could be listed at 7-1, a source said.

On Tuesday, Yabusele’s eyes went wide as he considered Poirier’s imposing size.

“He’s a tall guy and he can jump,” Yabusele said. “The way he finishes at the rim sometimes, the way he’s strong with the ball, it’s really something that not all the big men have. To be able to be really tough with the ball and finish strong and go to the line and make the free throws, it’s a plus.”

The Celtics have thrived over the years with big men such as Kelly Olynyk and Horford — and later, even Baynes — who are capable of stepping out and hitting 3-pointers, thus opening the floor for their ballhandlers.

Kanter, Poirier, and second-year big man Robert Williams are not perimeter shooters, however, so the development of Theis, who made 38.8 percent of his 3-pointers last season on just 68 total attempts, could be essential.

Theis has shown promise during his two years with the Celtics, but a knee injury two years ago that was followed by a foot injury last year limited him, and the presence of Horford and Baynes did not help him, either.

The Celtics’ frontcourt will have an unmistakably international flavor, with Kanter (Turkey), Theis (Germany), Poirier (France), and Yabusele (France).

“I’m more than happy to have another French guy but also another good player on the team,” Yabusele said of Poirier. “And I really think he can help us.”