Boston looked historically bad on offense in Game 1. The numbers back it up.

After Boston’s Game 1 loss at the hands of the Milwaukee Bucks — a 101-89 embarrassment on Sunday that was far worse than its final margin might indicate — I couldn’t stop thinking about how poorly the Celtics performed offensively, especially when juxtaposed with how well they played defensively. All things considered, giving up 101 points to the Bucks when Giannis Antetokounmpo plays as well as he did, and when guys are scoring as productively as Jrue Holiday and Bobby Portis were, is a win. Unfortunately, though, the Celtics played their worst offensive game in months. That’s what lost them their hard-earned homecourt advantage in a matter of 48 minutes. And that’s what has the potential to lose them a series to an undermanned opponent, defending champion or not.

Their lousy offense in Game 1 could be good news: maybe it means that the Celtics will turn it around for however long this series continues. Or, for you pessimists out there, it could be cause for a great deal of concern, a warning sign for what could be to come if the Bucks continue to bring the same sort of heat they brought on defense yesterday.

Much of what killed the Celtics in Game 1 was the fact that they failed to get anything going inside, much to the credit of Milwaukee’s swarming defense. Even when they went “small,” the Bucks had a significant size advantage, with Giannis almost always being the tallest player on the court and being able to contest any shot Boston could muster in the paint.

The same went for Brook Lopez on Sunday; he manned the area inside the arc with Garnettian poise, playing a huge part in deterring Boston’s closer shot attempts. The Celtics finished just 2-for-23 on contested two-point shots, the worst mark by any team in the postseason since 2017.

To make matters worse, they made just 10 of their 34 two-point attempts in Game 1, the second-fewest in any playoff game in NBA history (the 2017 Rockets made just nine against the Spurs). It’s also the fewest made two-pointers in any game in Celtics history (regular season or playoffs), per ESPN Stats & Info. They recorded an offensive rating of 89.2, the second-worst performance of the entire season. Boston shot a season-low 33 percent from the field and scored just 89 points, the fewest points they’ve scored since Nov. 13 (in a loss to the Cleveland Cavaliers).

“They were trying to take us out of certain sets, but we do like the spacing that it affords us,” Ime Udoka said after the loss. “Like I said, I don’t feel like our rim reads were the best tonight. We know Lopez is going to be back there. So we had some kick-outs and some drop-offs that we could have made and also some shots we missed close by the basket. Sped us up and I don’t feel we played with the best poise and composure overall. Got to see what they were trying to do as far as speeding us up and it kind of worked.”

It didn’t “kind of” work: it really worked. But it wasn’t solely Boston’s inability to score on the interior, nor its lack of composure, that sealed the team’s fate in Game 1. Frankly, the Celtics shot themselves in the foot by shooting so frequently from deep. They finished the game 18-of-50 from beyond the arc, which marks the most three-point attempts a Celtics team has ever launched in the playoffs. Ever. Those 50 attempts accounted for 60 percent of Boston’s total shots on the day, the team’s starkest proportional difference in shot distribution this season.

While the bulk of those three-point shots — 28 of them — came in the first half, practically every time they let a three fly, it felt like a desperation heave. It’s a coaching lesson as old as time: you can’t chip away at a double-digit deficit on the strength of a single shot. Yet far too often, the Celtics looked as though they believed that that exact approach was their best bet at working their way back into the game.

Which is exactly what Milwaukee wants you to do. They’re a team that is far more willing to give up shots from long range than anything inside. This season, the Bucks gave up a league-high 40.6 three-point attempts per game, the only team in the NBA to allow their opponents to shoot more than 40 shots per game from deep. But they were right of the mill when it came to how well those opponents shot it from distance: 35.6 percent was the per game average they allowed, a very down-the-middle clip that still implies a respectable defensive effort. (For reference, the Celtics allowed their opponents to shoot just 33.9 percent from three on a night-to-night basis, tops in the league but just 1.7 percentage points better than the 19th-ranked Bucks.)

The Celtics fell right into the trap.

Jayson Tatum and Al Horford combined to shoot 8-for-18 from three, an acceptable 44-percent clip. Grant Williams was two-for-four and arguably should have shot it more. And Derrick White, the team’s worst shooter since he was acquired at the trade deadline, showed real signs of life, nailing two of his three attempts from three and thus revitalizing the waning hope C’s fans had left in his offensive ability. It’s how the rest of the roster fared that should cause some concern, and perhaps a few extra spot-up shooting drills at practice over the next two days.

Marcus Smart shot just one-for-six from three — his lone bucket coming on the C’s third attempt of the game — looking like the Smart of old that would force a three without thinking about the better options that might be available to him as a passer. Payton Pritchard, who has arguably been the team’s most reliable three-point shooter over the last four weeks, went cold when the team needed his services the most. He missed four consecutive threes over a four-minute stretch to start the fourth quarter and was two-for-eight for the game from deep. This was the type of game in which Pritchard would have been most useful. Instead, he inefficiently faded into the background.

But for how inefficient the team was in full, it was Jaylen Brown’s day that was the most overwhelming disappointment. He was three-for-nine from three, but he made just one of his seven attempts in the first half. Brown most closely embodied the idea that one shot would reduce the deficit; his shots were forced, and he was as off as he’s been in a long time. (Odds are he won’t play this poorly again. Candidly, he can’t, or else Boston stands nary a chance in this series.)

Photo by Adam Glanzman/Getty Images

Perhaps the last few months of overwhelming dominance have caused some to don rose-colored glasses as it pertains to Boston’s shooting ability. Because despite the fact that the team shoots a ton from three — not to mention an alarming amount of long twos — they don’t shoot it all that well. They attempted the ninth-most threes per game in the league this season (37.1) but were 14th in three-point shooting percentage (35.6). They have two consistent deep threats in Tatum and Brown — even though he was horrendous on Sunday — a bevy of so-so slingers, and a few wild cards, namely Williams and Pritchard. The Celtics are inconsistent at best as a shooting team; they rely more on movement to create open shots as opposed to being truly good shooters.

To call the Celtics’ offensive output on Sunday historically poor may have sounded like an overreaction when it was considered immediately after the game. But by the numbers — and the looks of it as the game unfolded — it’s as accurate as it gets. And if it continues, the Celtics will be the victims of a historically disappointing collapse after undergoing a historically-impressive midseason turnaround.

After the game, Jayson Tatum made note of the fact that a series “is not won or lost off of one game, especially not Game 1.” But if this Game 1 was any indication, the Celtics will need to undergo a serious overhaul in the game plan in order to contend with the defending champs. So, no: a series cannot be won or lost based on the performance a team puts forth in its first game. But if that sort of performance persists, the series won’t be much of a series at all.

A good deal of history is at stake here. Boston can’t afford to be on the wrong side of it again.