The Celtics boast a deep enough roster to win without Kristaps Porzingis. But they’ve missed their rehabbing big man in one important area this season: rim protection.

Twelve games in, Boston ranks 18th in the NBA in blocks per game, 20th in blocks per 100 possessions, 18th in opponent field-goal percentage in the restricted area and 20th in opponent shooting percentage on defended field goals inside six feet.

Its rankings in those categories last season: first, first, seventh and second, respectively.

After the Celtics were outscored 68-20 in the paint and surrendered 20 offensive rebounds Tuesday in a 117-116 loss to Atlanta, head coach Joe Mazzulla said his team’s defense at the rim “absolutely” needs to improve.

“We got cross-matched on them a few times, but (the Hawks) got rebounds and layups on everybody,” Mazzulla said. “Bigs, smalls, mediums. They just outplayed us, both ends of the floor.”

Last season, Celtics opponents’ shooting percentage on shots at the rim was 6.1% worse with Porzingis on the court than off it, per Cleaning the Glass. That disparity ranked in the 95th percentile of all NBA players.

Boston doesn’t have another player who can replicate Porzingis’ rare skill set, and with him unlikely to return from offseason leg surgery until December at the earliest, Mazzulla has tried out several different frontcourt configurations in his absence.

Recently, he’s leaned more on emerging center Neemias Queta, who’s leapfrogged Luke Kornet and Xavier Tillman as the top option behind Al Horford. The loss to Atlanta was Queta’s fifth consecutive game with at least 20 minutes played.

Kornet, meanwhile, logged just 10 total minutes over the last two games after missing one with a hamstring injury, and Tillman has largely faded from the rotation despite starting last Friday against Brooklyn, with three healthy DNPs in the last seven games and 18 total minutes played during that span.

Queta has been Boston’s most effective rim protector so far this season, with opponents’ shooting percentage in those situations much lower with him on the floor (-7.0%) than Kornet (-2.3%), Horford (+3.9%) or Tillman (+7.9%).

But his defensive rebounding numbers have been lacking. Opponents have recovered offensive boards at a 7.7% higher rate with Queta in the game, per Cleaning the Glass, which ranks in the fourth percentile league-wide. Horford’s been far better there: -7.1%, 93rd percentile. Kornet is an even 0.0%.

The Celtics will get Porzingis back soon enough, and improvements in these areas should follow. But until then?

“Individual defense is the most important thing,” Mazzulla said. “We’re playing smaller, so we have to be better at our individual defense.”