You heard the question as rivals eyed the standings and maybe even jockeyed to avoid them:

Why is everyone so afraid of the Brooklyn Nets?

Well, that’s why: Even when perhaps the world’s best player shoots 9-of-24 — even amid a season in which it has been impossible for them to develop any momentum — they take the No. 2 seed to the wire in Game 1 of what could be a riveting first-round series.

All it took was one of their two (available) stars compensating for the shooting struggles of the other, plus good games from two role players — Nic Claxton and Goran Dragic.

It felt like Game 5 of a late-round series. These teams know each other. They attacked in the ways you expected. The coaches did not leave much low-hanging adjustment fruit.

The end result was a gut punch for the Nets. The Boston Celtics are the more complete team. They went 33-10 in their last 43 games, mauling opponents by 13.5 points per 100 possessions — almost double the margin of the No. 2 team (the Phoenix Suns, an NBA metronome) in that span. Their rotation has been consistent for months.

You need similar cohesion to beat a team this good four times in seven tries. The Nets have enjoyed cohesion for zero seconds. Steve Nash is still stitching lineups — choosing between undersized three-guard groups heavy on shooting, and stouter defensive units featuring two non-shooters Boston’s vice-grip defense can ignore. Every choice is fraught.

Joe Harris’s absence has loomed over this entire season; he might be the best shooter among Brooklyn’s perimeter role players, and better than all but Bruce Brown on defense. The potential presence of Ben Simmons looms over this series. The Nets are hopeful he might return, maybe soon, and he might unlock the center-less lineups that probably represent the team’s highest ceiling.

All those uncertainties are why snaring Game 1 seemed urgent for the Nets once they took the lead. Their margin for error is a little smaller. Simmons would widen it some.

My best guess would be Brooklyn brings Simmons off the bench, at least at first, if he returns. The team has finally settled on a starting five in Kyrie Irving, Seth Curry, Bruce Brown, Kevin Durant, and Andre Drummond. I would be mildly surprised if the Nets upended it to accommodate a unique (to be polite) player who has not played in 10 months.

Even a limited Simmons would help the Nets get out in transition, and fortify them on defense and on the glass. (Boston’s overall size helps in ways that might be tough to notice in transition defense. They don’t have to worry about finding specific matchups; they each can take whichever opposing player is nearest. The Nets don’t run a ton, but they are efficient when they do.)

Boston smoked the Nets on the glass in Game 1. That was baked into the series. Boston ranked 11th in offensive rebounding rate, the Nets dead last in defensive rebounding. It will only get worse if Robert Williams III returns. That said, Brooklyn can be more diligent gang rebounding.

Daniel Theis, normally not much of a threat, plucked four offensive boards in Game 1. The Nets went the unconventional route of guarding him with Curry — a gambit that allowed them to put their two best defenders, Durant and Bruce Brown, on Tatum and Jaylen Brown. (Irving guarded Marcus Smart, with Drummond on the resurgent Al Horford — who logged a shocking 41 minutes! That seems unsustainable, even without back-to-backs.)

The Celtics could and should have gone at that matchup more by using Theis as a screener for Brown and Tatum — forcing the Nets to choose between getting themselves into rotation, or switching Curry onto one of Boston’s stars.

I wonder if Boston will even get that chance now. Brooklyn could rejigger matchups to eliminate the Curry-Theis weirdness. It could shift Curry onto Smart; Irving to Jaylen Brown; Bruce Brown onto Tatum; Durant onto Horford; and Drummond to Theis. That would end Theis’ volleyball game on the glass and spare Durant the burden of guarding Tatum — at the cost of slotting a smaller guard onto Jaylen Brown.

When it has nothing better going — and when Tatum rests — Boston might try posting up Jaylen Brown and even Grant Williams when the Nets hide smaller players on them. Both can playmake if the Nets send help. Jaylen Brown brutalized Bruce Brown on one post-up. Anytime Jaylen Brown or Tatum ends a Boston defensive possession on one of Brooklyn’s undersized guards, they should sprint the floor and cement that matchup.

Tatum played 45 minutes in Game 1, including the entire second half. Boston barely outscored opponents in the regular season when Jaylen Brown played without Tatum. The Nets have to win those minutes. The Celtics have to win the non-Durant minutes — which they failed at in Game 1, even though Tatum played every second Durant rested. Expect the Celtics to focus more on those minutes in Game 2 — to throw more help at Irving, and perhaps make sure Theis and maybe Payton Pritchard are on the bench.

(By the way: How many players are better than Tatum right now? There is Giannis Antetokounmpo, Durant, Joel Embiid, Nikola Jokic, and probably Luka Doncic. Is that the whole list? Your mileage may vary on how to rank Stephen Curry and LeBron James. Tatum was probably better than both this season — it’s close — but those guys are legends. No one wants any part of James in one game. Curry is on the outer edges of his prime, powering an offense unlike any other in stylistic terms. But Tatum has surpassed James Harden, Jimmy Butler, Damian Lillard, Anthony Davis, and Paul George. He’s above the best young guys, including Ja Morant, Karl-Anthony Towns, Devin Booker, Trae Young, and Donovan Mitchell. His companion in terms of overall rank might be healthy Kawhi Leonard.

This is Tatum’s series. He’s guarding Durant and serving as Boston’s No. 1 option on offense. That is what apex superstars do. He blocked Irving and Durant on jump shots in Game 1. Durant’s own guy swatting his jumper is unheard of. Danny Ainge took flak for some missed draft picks and an alleged tendency to hoard assets. Some of that was justified, much of it not. But the former Celtics president of basketball operations and his staff probably haven’t gotten enough credit for trading down to select Tatum — and getting another lottery pick in the process. That is an all-time masterstroke. Imagine if the Celtics had taken Markelle Fultz or even Lonzo Ball?)

Boston did well getting Tatum matched against Brooklyn’s small guards. The Tatum-Marcus Smart pick-and-roll — with Tatum as ball handler — might be Boston’s defining play of the series. Boston runs the reverse quite a bit too, and the Nets need to be better ducking Tatum’s screens for Smart — and maintaining their matchups. You can’t duck Smart’s screens for Tatum; that gifts Tatum easy pull-ups.

Boston mixed up its entry points to the Tatum-Smart two-man game. The Celtics surprised the Nets on two straight possessions by having Smart enter the ball to Tatum on the wing, and then scurry down to screen for him:

Smart’s pick mashes Durant, freeing Tatum. The Nets were ready for this on the next possession; Tatum preyed upon their expectations:

That Tatum spin-away is becoming one of his signatures.

For the season, Boston scored 1.401 points per possession on any trip featuring the Tatum-Smart pick-and-roll — No. 1 among 426 two-man combinations with at least 100 reps, per Second Spectrum. The Tatum-Derrick White pick-and-roll has the same effect, since White is often the hiding place for opposing point guards.

The Nets might try to avoid switching — even if it means Smart’s guy lunging to corral Tatum, briefly leaving Smart open and triggering rotations behind the play. When Brooklyn dialed in, it managed to defend without conceding the switch; this was a really nice bit of late-game defense:

Of course, Tatum can kick to Smart, and let Boston’s point guard take it from there in 4-on-3 situations. Boston has the collective passing chops now to exploit that. It’s incredible that in the span of 40 games, Boston has transformed from a team that didn’t pass enough to one that sometimes overpasses. (You can see White’s confidence in his jumper wavering.)

But Boston is still only a so-so shooting team around Tatum and Brown, and the Nets know it. They slid away from pretty much everyone else to crowd Boston’s stars, sometimes coaxing kickout passes. Brooklyn is betting on their ability to contest those shots, and on those Celtics missing:

(That’s another method of getting a small guard onto Tatum: running Tatum off a pindown from that guard’s man, in this case Grant Williams. Brooklyn has to either switch, or chase Tatum over — granting him a runway. Both are bad choices.)

Boston’s spacing around those Tatum and Brown isolations was sometimes clunky.

Brooklyn likes to mismatch hunt too; Boston just has fewer weak spots. White is a really good defender, but too short for Durant (who isn’t?) and not physical enough to disrupt Durant’s rhythm. Durant went at White every chance he got, to great effect.

Theis and Horford might be the pivot points of the series. The Celtics love to switch everything, but they have been hesitant (by their standards) to switch their bigs onto Durant and Irving. The Nets should prod that more. If Boston’s bigs drop back in pick-and-rolls, Irving and Durant rain pull-up fire.

Make enough of those, and Boston will switch. That starts an interesting cat-and-mouse game. Irving and Durant can roast Boston’s bigs off the bounce, but they sometimes choose not to — settling for pull-up 2s instead.

You can understand why:

Irving has Horford beat, but he sees a thicket of defenders. Theis leaves Drummond to clog the paint, and Smart takes an extra step from Brown to cover for Theis. That should expose Boston to some drive-and-kick meanness, but the Celtics are long, rangy, and very smart; they might be the league’s best help-and-recover team — experts at showing help without overcommitting, or revealing any easy passing lanes. Even here, they nudge Irving away from Durant, and stay within range of every Net.

Boston can also switch those bigs onto Irving and Durant, and spring hard double-teams on them — to quell a run, or just to keep Brooklyn off balance. The Celtics also tried pre-switching Horford out of pick-and-roll as his man jogged up to screen.

Swapping out one non-shooter opens the floor wide for Brooklyn. Those lineups are tiny — compromised on defense. Even the teensy four-guard lineups Brooklyn favors when Durant rests have both Bruce Brown (serving as power forward) and Claxton. Those lineups generally aligned with Tatum’s playing time — making it easier for Tatum to play mismatch ball. (I thought the Nets might try to avoid such overlap with Tatum.)

Boston stayed pretty big against those groups, producing some awkward matchups — including Horford guarding Dragic. Dragic spent most of that time chilling in the corner. The Nets might peck at that matchup by having Dragic run around pindowns, or set ball screens. Of course, the Celtics would probably switch all those actions. Boston could also go smaller, with only one of Horford, Theis, and Grant Williams. The Smart/White/Brown/Tatum/Horford group closed Game 1 and went plus-7 in 13 minutes.

With two non-shooters, the Nets have to max out on creativity and high-level anti-switch devices. Slipping screens before really setting them — getting ahead of the switch — is probably the most common anti-switch technique. Irving got one layup in Game 1 by using another: faking toward a ball screen, baiting the switch, and then zipping away from the screen — and away from both defenders. The Nets need more of that, plus the kind of set pieces that involve several players of different sizes — sewing confusion:

The other options are drastic: unearthing LaMarcus Aldridge for some combination of size and shooting (he could in theory play alongside Bruce Brown or Claxton/Drummond), or saying to hell with it and playing Durant at center with four guards.

That is where Simmons would change their team. The current Durant-at-center lineups are just too small. Simmons is 6-foot-11. He’s an elite defender and rebounder, though not quite the rim protector you’d hope (yet). He can play the Bruce Brown role on offense, only above the rim (if he’s not afraid to get fouled). He’s a good enough playmaker that the Nets might be able to play him with Brown. (The Nets have enough shooting to try Simmons with one of Claxton and Drummond in bigger lineup types.)

You can win with Irving, Curry, Guard X, Durant, and Simmons — whether Guard X is a defense-first guy like Brown, or one of Dragic and Patty Mills.

Alas, we don’t know if or when Simmons might return, or how much he’ll give. One or two such “ifs” make for an uphill battle against a team as together and buttoned-up as Boston — especially without home-court advantage. Even if Brooklyn loses tonight, it still has three of the remaining five games at home. It has the firepower to beat anyone.

It’s just hard to imagine these Celtics losing four times in five games. The Nets may need Game 2.