Entering last season, plenty of uncertainty surrounded the Celtics’ frontcourt after the departures of Al Horford, Luke Kornet, and Kristaps Porzingis.

Even the man who constructed the roster, Brad Stevens, wasn’t sure how it would unfold.

“We’ll see how that looks,” Stevens said at the time. “I don’t know how the frontcourt is going to play itself out right now. I can’t predict it.”

It was far from perfect. The Chris Boucher and Nikola Vucevic experiments failed rather miserably, while Xavier Tillman was shipped to Charlotte at the deadline as the Celtics looked to dip below the luxury tax.

Still, the Celtics got far more out of their frontcourt than they may have expected, at least in the regular season.

A big part of that was Neemias Queta, whose 13.2 net rating led the Eastern Conference among players with at least 60 games played, trailing only Victor Wembanyama (17.0), Shai Gilgeous-Alexander (16.3), and Chet Holmgren (16.1) league-wide.

Queta averaged 10.2 points, 8.4 rebounds, 1.7 assists, and 1.3 blocks per game, surpassing his combined totals in points, rebounds, assists, steals, and blocks from his first four NBA seasons. He finished fourth in Most Improved Player voting and received seven votes for the All-Defensive team, earning a 4-year, $56 million contract extension over the summer.

The other key was Luka Garza, who set career highs in points (8.1), rebounds (4.1), field-goal percentage (57.7%), and three-point percentage (43.3%) per game.

The Celtics hope those two can build on their breakout seasons.

But just banking on continued growth wasn’t enough. Stevens and the front office further shored up the frontcourt by adding Mitchell Robinson, arguably the best center on the free-agent market, on a three-year, $47 million contract.

The eight-year veteran averaged 5.7 points, 8.8 rebounds (4.2 offensive) and 1.2 blocks in 19.6 minutes per game last season, playing a key role in helping New York reach the Conference Finals in 2025 and snap its 53-year title drought.

Robinson is one of the NBA’s best offensive rebounders.

He was one of only five players to grab at least 250 offensive rebounds last season, finishing with 252. His 20.1% offensive rebounding percentage led the NBA. He also led the league in total rebounds per 36 minutes (16.1), offensive rebounds per 36 minutes (7.7), total rebounds per 100 possessions (22.2) and total offensive rebounds per 100 possessions (10.6).

“I just want to add what I did in New York. The dirty work. The grit. The grind,” Robinson said. “I’m just ready to go.”

With the addition of Robinson, and the hope that Queta and Garza can build off their breakout seasons, the Celtics have much more confidence in their frontcourt entering this season.

“Their versatility. I mean, they’re different kinds [of players],” Mazzulla said when asked what excites him about this group. “Obviously, Mitch’s resume speaks for itself. If you look at Neemi and Luka, they’re both significantly better players than they were at the beginning of last season. Credit to them and their work ethic. With guys you have coming back, you want them to take that next step. They both had great off seasons. They both deserve to be given more responsibility within the framework of our team. But we have three different kinds.”

Garza can stretch the floor. His 43.3% three-point percentage led all centers with at least 100 three-point attempts, according to NBA.com.

Queta and Garza provide vertical spacing and elite rim protection. Queta had 119 dunks, shooting 65.3% from the field with an average shot distance of 3.9 feet. Robinson had 97 dunks, which accounted for 51.5% of his field-goal attempts, while a league-high 92.2% of his shots came from 0-3 feet. His average shot distance was one foot from the rim, the closest mark of any player in the NBA.

Queta was one of just 12 players to record at least 100 blocks last season, while Robinson had 70 blocks in 60 games. All three are also elite screeners.

“Obviously, we all bring different things to the table, and we’re going to do those things when called upon,” Garza said. “I think throughout the year it’s just going to be about us having that connection as a group that it’s a mindset, it’s a pride we have to anchor the paint and do the best we can to control the rim, protect the rim and control the glass.”

Mazzulla believes center is the most important position on the floor, and he feels good about where the Celtics are at the position.

“I think the most important position in the league is your center position,” Mazzulla said. “They’re involved in every single pick-and-roll on both sides of the floor. They control your offensive and defensive rebounding numbers, and most adjustments run through them. So those guys carry a lot of pressure, expectation, and responsibility. And I think the three of them are ready to handle it.”

When asked how the group can complement each other, Queta pointed to their collective toughness and physicality.

“Toughness, physicality. That’s something that we do really well — all three of us. We’re all pretty down-to-Earth guys. So I think that’ll mesh us pretty well,” Queta said. “I can’t forget about Amari [Williams] and Chris [Cenac Jr.], as well. I think our Big Fella University is pretty exciting. Those guys should be pretty reliable. Night in and night out, whoever gets called upon, I have 100% confidence that we’ll deliver.”