Avery Bradley is not actually this good, but he is uniquely important to Boston's specific collection of puzzle pieces. The Celtics' Game 2 letdown in Atlanta laid it bare: For a team built on the synergy and ferocity of its depth, sometimes it only takes one injury for everything to crumble.

The trickle-down effects of Bradley's injury extended beyond coach Brad Stevens playing R.J. Hunter and Terry Rozier in meaningful postseason minutes as cogs in lineups that had never logged a single second. Stevens started Marcus Smart in Bradley's place, a smart move, since Smart is the only perimeter player besides Bradley with the wheels to track Jeff Teague; Evan Turner is too slow, Jae Crowder is a shell of himself due to an ill-timed ankle injury, and the Celtics don't want Isaiah Thomas chasing Atlanta's shifty point guards.

But Game 1's random outburst aside, Smart can't shoot. Boston's two starting bigs, Jared Sullinger and Amir Johnson, are at their best operating inside the foul line -- meaning their defenders can hang there, too. Add Smart's emboldened defender to the jumble, and poor Thomas had no path to the rim.

Stevens realized it immediately, and barely three minutes into the game, he went small, swapping Evan Turner in for Johnson. Problem: Turner can't shoot, either. Going small with three non-shooters, including two on the wing, brings none of the benefits of small-ball. It just makes you smaller, which in a vacuum is bad, even in the modern NBA. There's a reason the key lineups featuring both Smart and Turner also included at least two of Bradley, Jonas Jerebko, and Kelly Olynyk -- also missed, due to a shoulder injury.

The Hawks' defense, No. 2 in the league behind the San Antonio Sharktopuses, is built specifically to strangle teams who can't shoot. The Hawks leverage the speed of Al Horford and Paul Millsap by having them attack pick-and-rolls out to the 3-point arc, with help defenders behind them flying into the paint to bump opposing big men rolling open toward the rim.

There is a leap of faith, and a deep team-wide trust, in leaving shooters open on the weak side to clog the paint. The Hawks hope their four-armed trap will force opposing ball-handlers to pick up their dribble far from the hoop, and search for any release valve. That outlet won't be in the paint. It will be a temporarily open player, all the way across the court, and that ball-handler -- say a little guy like Thomas -- will have to lob a brutal long-distance pass to get the ball there.

The Hawks wager that they can outrun that pass, recover onto those open shooters, and stay in front of them as the shot clock dwindles. Teams who dot the entire floor with good shooters stretch that defense to to its breaking point; the Hawks gave up more 3-point attempts than anyone last season, and it scared them to death.

"We did not like giving up so many 3s," Mike Budenholzer, the Hawks' coach, told me in March. "But it's a constant battle. You can't pressure the ball like we do without exposing yourselves a bit."

Teams with poor shooting can't expose the Hawks that way. Atlanta buries those teams, and without Bradley, the Celtics go from a so-so shooting team to perhaps the worst one in the league outside Philly and Memphis. Whenever one Celtic got some traction toward the rim, he found an extra body walling off his path -- as Kent Bazemore does here, veering away from Turner to muck up Smart's driving lane:

This Smart/Johnson pick-and-roll has no hope with Bazemore sneaking into the restricted area, away from Turner in the right corner, before the play even really gets started:

Smart kicks to Crowder, who might be a better than 50-50 bet to drive past Millsap if he were healthy. He's not, but just in case, Bazemore stations himself in Crowder's way rather than recovering onto Turner.

The Hawks made that play more complicated than it needed to be. Kyle Korver, guarding Smart, could have just ducked under Johnson's screen, daring Smart to pull-up for a brick. Atlanta has done that a ton in this series against Smart, Turner, and even Crowder, who slumped to 33.6 percent from deep after starting hot.

The Celtics are an easy team to shell, doubly so without Bradley. They fit a lot of stuff into every possession -- a whir of hand-offs, cuts, and pindowns. Duck under everything, and all the motion amounts to nothing; no Celtic can take the ball within 15 feet of the rim, leaving them desperate. Boston's mini-rally in the second quarter, which was kind of like a swimmer barely avoiding getting lapped, came mostly on the back of Turner mid-rangers and Johnson post-up junkballing. That is not sustainable on the team level. Sneaking under a screen for Bradley at least carries some risk.

The Hawks have even gotten brave switching Millsap onto Thomas, volunteering themselves into what looks like a fatal mismatch. But Millsap can hang with quick feet and grippy hands, and even if Thomas blows by him, the Hawks are ready with help defenders:

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That switch carries another benefit: if Boston misses, the Hawks might be able to catch them with a smaller defender on Millsap.

That's the rub for Boston now: Thomas is both their best shooter, and their best ball-handler -- by far. That's a wonderful combination -- it sounds like Steph Curry! -- but it can actually be sub-optimal in the wrong context. If Thomas has the ball, that means all five defenders can focus on him, without leaving any good shooters open. If he doesn't have the ball, nothing of consequence is happening.

Boston opened the second half of Game 2 with three straight Smart pick-and-rolls. That was not an accident. It was a last-ditch bit of exploration -- an attempt to see if they could get anywhere by positioning Thomas, now their best shooter, away from the ball, so that at least one Atlanta help defender had to stay out of the paint. For one possession, it worked:

Boston slid Thomas over to the weak side, slotting his defender, Teague, into help position -- and thrusting a choice upon him: dive down onto Johnson, abandoning Boston's most dangerous shooter, or stick to Thomas and leave the rim naked.

Unfortunately for Boston, Smart isn't ready for that sort of responsibility. He's added some craft to his pick-and-roll game, but he still forces nutty shots in crowds, and turns the ball over a ton; Smart coughed it up on 20 percent of the pick-and-rolls he finished this season, 137th among 178 guys who completed at least 50 such plays, per Synergy Sports.

Turner is miles better, and the Celtics might consider starting him over Smart -- if Stevens even continues to start both Johnson and Sullinger, which may be a losing proposition going forward. But starting Turner would imperil Boston's defense. They don't trust Thomas to guard Teague or Korver, and when they briefly tried him on Korver in Game 2, Atlanta's sharp-shooter immediately roasted him and drained an open 3.

Turner is not quite fast enough to track Korver through the thicket of picks Atlanta sets for him, and he has no shot sticking with Teague and Dennis Schroder. If Boston tries to get away with Turner there, the Hawks might think about ditching their usual pick-and-roll orchestra and letting their point guards go one-on-one.

Atlanta's coaching staff knows how easily Teague and Schroder can beat guys off the bounce on their own, skitter into the paint, and create good offense. It's an internal tug-of-war for them. Isolation play cuts against their identity of sharing, and the team is unsure if either point guard can strike the right balance between hunting his own and driving-and-dishing for others.

But having Turner guard Teague would weaponize those isolations. Bottom line: the Celtics are most comfortable stashing Turner and Thomas on Bazemore, but only one of them can get that job. In some sequences, it will have to be Thomas. These are solvable issues with Bradley.

On offense, the Celtics have paths to better shooting. They could play Jerebko more at power forward, both alongside Crowder -- their primary small-ball 4-- and when Crowder rests. If Olynyk comes back, they could triple-down on shooting by playing Jerebko and Olynyk together -- with Olynyk as a shooting center, a look Boston has used often this season.

If Olynyk can't return, Stevens might revisit a look he flashed briefly at the end of first half in Game 2: a super-duper small lineup, with Jerebko at center, and Crowder at power forward. Boston busted that out now and then in the second half of last season, when most of their traditional bigs were injured, and discovered that it worked with Thomas driving the bus -- at least in small doses.

"It was quick and fast, and hard for teams to play against," Stevens told me in the fall. "There were things we struggled with, but that's part of the game."

The Hawks would probably respond by switching almost everything against that group. They've switched more this season -- if you catch a Hawk yelling out "red!" late in a possession, that's code for "switch!" -- even though it doesn't fit with how San Antonio molded its defense during Budenholzer's tenure. Horford and Millsap can keep up with most guards.

"I really wish they would mic up the court, because then you could really hear how much the good teams talk," Bazemore told me. "Switching can work, and it's cool, but only if you communicate well."

(As an aside, I'm intrigued by how Detroit might handle as similar five-out lineup, with Kevin Love at center, during Game 2 tonight. Andre Drummond isn't as comfortable switching onto perimeter players, but he was out of his element chasing Love on pick-and-pops. Jeff Van Gundy suggested his brother hide Drummond on a wing like Iman Shumpert, but that's the ultimate Catch-22 in a big-versus-small/spacey battle: shifting Drummond away from center stage is safer, but it also takes him away from the rim, where almost all his value lies).

Boston could punish those switches; Thomas beating Horford off the bounce is more threatening if he has Jerebko, Olynyk, and Crowder around him. But the math would probably lean toward the Hawks. None of Boston's players scare you posting up mismatches, but Atlanta's big men do; the smaller Boston goes, the more Horford and Millsap can default to bully-ball. If the pick-and-roll goes nowhere, the C's could try more Golden State-style "split cuts," where two players away from the ball run toward each other and burst apart in unpredictable patterns.

Not all of this stems from the loss of Bradley, but a lot of it does. It's ironic that this is happening against Atlanta, a better version of Boston that experienced something similar during the death spiral of their dream season last year. The ultimate greater-than-the-sum-of-its parts team fell apart when a couple of those parts -- and not even the main ones -- fell away.

Depth is funny like that. Being deep doesn't mean you can sustain injuries better than shallow, top-heavy teams. It might mean the opposite: if every player lifts up every other player, or fills some gap no one else can fill, the loss of one or two guys can have an outsized impact.

Stars solve everything. That's why everyone wants them. It's why Philly just threw away three years. The Cavs suffered calamity after calamity last season, and it didn't matter until halfway through the Finals.

But LeBron is not just a star. He's a top-10, and possibly top-5, all-time player. One normal star doesn't get you that far. Ask Anthony Davis, Love, James Harden, DeMarcus Cousins, Carmelo Anthony, and last year's Thunder team. What happened to Atlanta last season, and what's happening to Boston now, doesn't invalidate their mode of team-building, or suggest every good team should just throw their pieces away and race Philly into the toilet.

Every team needs the luck of good health and matchup advantages to gut through four playoff series. Even the mighty Warriors are one ankle sprain away from being just another good team. At some point, one of these teams without a top-10 player will run into the right combination of breaks in May and June: near-perfect health, friendly matchups, and maybe an injury to a key opponent.

It's a low-odds play, obviously. So is every path to a championship. Again: one "normal" superstar ain't doing it on his own. What is a star, anyway? Millsap and Horford aren't superstars, but they are two of the 20 best players in the league, and Millsap this season was damn close to cracking the top 10. (By the way: remember when Utah let him walk for nothing, in his prime, by the way? Can we stop reading holier-than-thou pieces about how the upstanding Jazz would never, ever tank?).

They are versatile enough for Atlanta to play any style, against any opponent. The Hawks are unbothered by your small-ball gimmickry. Amp up the perimeter talent around them just a bit, and Atlanta could be a great team. But that's a conversation for the offseason -- a conversation about cap space, trade assets, and whether Schroder might one day pop.

That offseason appears to be at least a couple of weeks away. This Boston team fights like hell, believes in itself, and plays together. They're going home now. They won't roll over. But at something less than full health, they're fighting from way behind.