Eddie House identifies ‘tiny red flag' for Celtics early in season

When you're the reigning NBA champion, you hold yourself to a higher standard. So, while the Boston Celtics own the second-best record in the Eastern Conference at 9-3, there's still room for improvement.

That much was evident Tuesday night, when the Atlanta Hawks handed the Celtics a stunning 117-116 loss at TD Garden in their first game of NBA Cup group play.

How did a Hawks team missing three of its starters (including Trae Young) upset Boston as a 16.5-point underdog? For one, the Celtics committed a whopping 20 turnovers that led to 19 Atlanta points. But the C's also got dominated on the glass and in the paint; the Hawks racked up 20 offensive rebounds to Boston's six and scored 68 points in the paint to Boston's 32.

The deciding score for Atlanta was -- you guessed it -- an offensive rebound and a second-chance bucket from Onyeka Okongwu, who elevated over Jrue Holiday and Jaylen Brown for a put-back tip-in.

Tuesday night wasn't the first time Boston has been beaten in the paint this season. In fact, The Celtics are allowing 52.2 points in the paint per game (24th in the NBA), while scoring just 39.8 points in the paint per game (30th in the NBA) for a differential of negative-12.4.

And if you ask former Celtics guard Eddie House, that's cause for at least some concern.

"Right now we're giving up 52 points in the paint per game. That is bottom-third in the league," House said after Tuesday's game on Celtics Postgame Live. "And then we're only (scoring) 39 points (in the paint).

"I know we shoot a lot 3s, so I understand that. But we're last (in points in the paint). So, we have to find some sort of balance. It's OK sometimes to get to the rim to get an easy bucket, to get a deuce. We don't always have to shoot a 3.

"This isn't overreacting. I'm not gonna push a panic button on this. But these are little tiny red flags, and while they're small, you want to stomp them out so they don't become big red flags that could affect you later on in the season -- or something that somebody could look at and say, 'This is how you can attack this team. This is how you can beat this team.'"

The Celtics take (and make) the most 3-pointers in the NBA by a significant margin, so it makes sense why they rank last in paint points per game. But their interior defense and rebounding appear to be areas of weakness through 12 games this season, as highlighted by the stats below:

• Celtics offensive rebounds per game: 9.9 (19th in the NBA)
• Opponent offensive rebounds/game: 10.6 (T-13th)
• Points in the paint/game: 39.8 (30th)
• Opponent points in the paint/game: 52.2 (24th)
• Second chance points: 13.8 (19th)

So, what's the solution? Obviously the return of big man Kristaps Porzingis will help, but the Celtics need more from their big man rotation of Al Horford, Neemias Queta and Luke Kornet, who have had their moments but overall have lacked consistency.

Jaylen Brown, meanwhile, believes it's a matter of effort instead of personnel.

"We switch, so we’ve got to fight," Brown told reporters after the game. "We’re a team that likes to be able to switch, but you’ve got to rebound, and you’ve got to be able to fight."

The Celtics' interior defense will be tested again Wednesday night against a Brooklyn team that racked up 54 paint points against Boston while taking the C's to overtime last Friday night.