The Celtics didn’t need to be sharp Monday night.

They just needed to be professional.

Boston built an early lead, controlled the margins, and dispatched the Bulls 115-101 at TD Garden, extending its surge to eight wins in nine games and reaching 23-12 on the season.

It wasn’t elegant. It wasn’t clinical. But it was composed, and that composure has defined the Celtics lately.

Here are four takeaways from Boston’s win over Chicago (17-19):

If you only looked at the shooting numbers, this game would make no sense.

The Celtics shot just 35.7% in the first half. They weren’t spacing the floor particularly well, and they didn’t find much rhythm early.

None of it mattered.

Boston crushed Chicago in the areas that don’t show up in highlights. They dominated the glass 64-49, including a massive 20-6 edge in offensive rebounds. That turned into a 26-12 advantage in second-chance points, allowing the Celtics to build separation without ever catching fire.

They also capitalized on mistakes, winning points off turnovers 19-8.

This is exactly what Joe Mazzulla means by “the margins.” Boston didn’t outclass Chicago - they outworked them. When shots aren’t falling, focus on details to close out games early.

Anfernee Simons continues to look more comfortable by the night.

The reserve guard poured in 27 points off the bench, shooting 9 of 16 and draining eight threes. More importantly, his scoring stayed in the flow - no forced plays, no momentum-stalling choices.

The defensive concerns haven’t vanished, but they’ve faded. Simons has competed on that end, stayed focused, and held his ground as Boston stacks wins.

Now, he’s not just a spark. He’s a steady weapon - and that matters with this team’s offensive hierarchy.

Jaylen Brown: ‘I’m the best two-way player in the game’

Jaylen Brown Sends Message in LA, Torches Clippers for 50 in 146-115 Win

What 'Starter' Really Means for Jordan Walsh on This Celtics Team

Coming off a 50-point masterpiece in Los Angeles, this was always going to be a tough follow.

Jaylen Brown struggled from the floor, shooting 6 of 24 and 3 of 14 in the first half. It was one of his toughest shooting nights this season.

Still, Brown found ways to contribute - 14 points, 8 rebounds, 4 assists - and never hijacked the game trying to chase efficiency.

That’s growth.

Great players have bad nights. Great teams survive them. Boston never wobbled, never chased, and never needed Brown to rescue them.

And yes, he’s still one of the best two-way players in the NBA.

For the second game in a row, Sam Hauser started as the fifth man, moving Jordan Walsh to the bench.

Walsh still played meaningful minutes, logging 18 and contributing 5 points and 5 rebounds, but this still feels like a situational decision rather than a permanent one.

Walsh’s energy remains valuable. Hauser’s spacing alters the floor's geometry.

Mazzulla is clearly comfortable toggling based on matchup - and that flexibility is a strength, not a concern.

The Celtics didn’t flex Monday.

They had no reason to.

They handled business, controlled what they could control, and moved on with another win - exactly what good teams do during the grind of the season.

Boston will look to keep that rhythm going Wednesday night against a Nikola Jokic-less Nuggets team (24-12) at TD Garden.

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Tom Carroll is a contributor for Roundtable, with boots-on-the-ground coverage of all things Boston sports. He's a senior digital content producer for WEEI.com, and a native of Lincoln, RI.