Lowe: Why the Boston Celtics' fallback isn't actually their history-making offense

Most scrutiny of the Boston Celtics -- including the generally muted reaction to their 12-2 scorched-earth run through the remains of the East this postseason -- centers around the style and substance of their offense.

The fretting transcends the Celtics on the macro level, leading to debates about shot selection and basketball modernity, and narrows on the micro level around the foibles of Jayson Tatum.

Boston attempted 240 more 3s than any team this season. (The Dallas Mavericks, their Finals opponent, were No. 2.) When they hit something approaching 40%, they appear unbeatable. This was, after all, the No. 1 offense this season and in NBA history.

When they slump from deep, they sometimes look vulnerable -- to the degree a 64-win juggernaut can ever look vulnerable. Do they have a fallback plan? They were 26th in shots at the basket. They don't get to the line much. They are an average offensive rebounding team. They were 29th in forcing turnovers on defense, which means they are almost entirely dependent on running after rebounds to generate transition points.

For other elite teams, the fallback plan is giving the ball to their apex superstar and asking him to create magic. That is where Tatum is perhaps not quite the player his harshest critics want him to be -- the kind of tall ball handler who does everything at an elite level. He is not, in other words, the sort of all-consuming offensive force Boston is about to face in the NBA Finals: Luka Doncic. Boston for the first time in these playoffs will not enter the series with the best player.

Tatum is not far from that. He deserved his first-team All-NBA spot -- his third straight. He is between the fifth and ninth best player in the world, depending on how you rate some of his peers.

He's a good passer, not a great one. He can settle for tough contested 2-point jumpers early in the shot clock, and he doesn't quite make those shots at the rate of some of the recent greats who also rely on them -- including peak Kevin Durant and Kawhi Leonard.

To the credit of both Boston and Tatum, that has not mattered much. Tatum has been more diligent about putting his head down and getting to the rim against friendly matchups. Every Boston crunch-time loss felt like a landmark event -- a referendum on its offense -- but that was because there were so few of them. The Celtics won in blowouts. They ranked sixth in points per possession in the final five minutes of close games. Were we all looking too hard for flaws that weren't there?

Maybe. But there were undeniable stretches of haziness -- where Boston's offense lacked purpose. Those stretches undid them in the two series losses that haunt them now -- the ones they will try to shove into the recesses of our memories by finally winning it all: the 2022 Finals against the Golden State Warriors, and last season's pratfall in the conference finals against the Miami Heat.

The Mavericks' offense never lacks purpose. Doncic is purpose incarnate. He has every shot, every pass, and the size and bulk (6-foot-7, 230 pounds) to execute all of them against any scheme. Every possession is targeted, calculated: Where is the weak spot? Doncic finds it, pokes at it and goes through his mental checklist of options -- including some no one else conceives until Doncic reveals them. You seldom come away from any Mavericks possession asking, Wait, what was the plan there?

It's why at times the Mavericks' offense can feel less potent yet somehow more reliable than Boston's.

But all the noise about Boston's offense -- what it is, what it isn't -- has overwhelmed the coverage of its real fallback: an elite, versatile defense. Perhaps Boston's greatest strength -- the thing that makes it distinct from lots of contenders, maybe including Dallas -- is that its best offensive players are also very good defenders. The Celtics do not have to compromise anything on one end to lift up the other.

That has not been ignored, exactly. Both Derrick White and Jrue Holiday made All-Defensive Second Team. Every Boston game is littered with references to its all-time great defensive backcourt, and its overall team-level performance. It is consistent, expected, a little less dependent on shot-making luck -- even if every defense can melt under an outburst of 3-point shooting fire.

There is mystery about Boston's offense. There is no mystery about Boston's defense. It is more fun to talk about the uncertain.

The Celtics ranked No. 2 in points allowed per possession, behind only the Wolves. They have been two points stingier in the postseason -- No. 2 among teams that advanced past the first round. That number would be at least a little worse had Boston faced Jimmy Butler, Donovan Mitchell, Jarrett Allen and Tyrese Haliburton over full series, but there is not much under the hood to suggest Boston is getting lucky on defense beyond opponent health woes.

The Celtics are No. 1 in opponent free throw rate and No. 2 in defensive rebounding rate. Their postseason opponents have actually shot better than expected based on shot location and the identity of the shooter on every attempt, according to Second Spectrum. The Heat, Cavs and Pacers collectively hit 45% on midrangers against Boston -- 13th among postseason defenses, and a number that would have ranked 27th among regular-season defenses, per Cleaning The Glass.

Defense has been Boston's bedrock since that 2022 Finals team went 26-6 to finish the regular season. The first signs that Boston's playoff run last season might get dicey came when that bedrock wobbled in its six-game first-round series win over the Atlanta Hawks. The Celtics made a few more mistakes every game than would be typical for a group of defenders so accomplished -- botched coverages, miscommunications on switches, blips of inattention.

Occasional malaise has dotted Boston's otherwise pristine defensive performance in reaching the Finals for the second time in three seasons. It can be a little cavalier straying from shooters. In their rare poor performances, Boston's transition defense has cracked:

When you switch so often, you are bound to have communication hiccups. In their (rare) down games, the Celtics have a few more than usual.

Whatever Holiday and Tatum were supposed to do there definitely did not involve letting Mitchell walk into a wide-open 3-pointer.

Ditto for the Celtics involved on these two walk-up 3s:

The best offenses are designed to produce mistakes. They run more stuff -- more chances for the defense to take a false step -- and have more shooting to punish any misstep. They are more well-versed in counters to switching schemes -- slipping screens early, faking picks, baiting the defense with false actions.

But Boston can ratchet it up, too. In their three series, the Celtics reached a higher gear on defense when they needed to. They elevated into a state of controlled frenzy, smothering every option, moving as one entity, responding to every opposing two-man action with the precise right read.

There is nowhere to go. The Celtics switch the first two actions but the real genius is that they do not switch the third -- that high-speed pitch play between Max Strus and Mitchell. Tatum, probably anticipating Strus might abort the screen early -- a classic anti-switch device -- stays home. Holiday sticks to Mitchell. That looks like nothing -- rote defense. But so much of great defense lies in the absence of mistakes -- in two defenders intersecting at full speed and deciding together, without a word, to do nothing fancy.

Whenever the Celtics could switch everything against the Pacers, Boston shut off the paint:

Indiana passed uselessly around the perimeter, gaining no traction:

Whenever they can, the Celtics so far in these playoffs have inverted matchups so that their centers defend non-threatening perimeter players -- leaving their armada of wings to guard the opponent's go-to screen-setters, and switch all pick-and-rolls. It is a tactic they embraced during their 2022 Finals run under former head coach Ime Udoka, with Robert Williams III nominally guarding punchless wings -- acting as rover, and allowing faster Boston defenders to switch pick-and-rolls.

Tatum guarded Evan Mobley for much of the conference semifinals, with Horford "guarding" Isaac Okoro. The Cavs could not find any consistent answers.

The Cavs try to ambush Boston by having Strus set a back screen for Caris LeVert on the weak side. The Celtics are ready; Brown and White switch in tandem. The switch leaves White on Strus' top side, opening up a backdoor cut. Horford snuffs that by sagging away from Okoro at the exact moment Strus might otherwise pop open:

Boston will likely try to mimic this scheme at times against Dallas.

The Mavericks present a challenge at an entirely different level than what Boston has faced in the last six weeks.

The Mavericks do not play any lineups against which Boston can safely switch everything. Their least dynamic offensive players can do more than their equivalents on Miami, Cleveland and Indiana.

In past matchups against Dallas, for instance, the Celtics have stashed their centers on P.J. Washington and Derrick Jones Jr. -- sticking wings on Dereck Lively II, Daniel Gafford and (when the Mavs have downsized) Maxi Kleber. If the Doncic/Lively pick-and-roll involves Brown and Tatum, that's a natural switch -- though Boston will have to be careful protecting the defensive glass.

The same could be true of an Irving/Lively two-man action that starts with Holiday on Irving and Tatum on Lively. Holiday and Brown can switch the Irving/Doncic two-man game. That switch gets dicier if White begins on Irving; Doncic has the size to bully White.

The point is that if Doncic wants to go after Boston's centers, he has to use someone other than Lively and Gafford as his screener to do it. That leaves those big men to linger around the basket; if Doncic's pick-and-roll partner -- Jones, Washington, Josh Green, whoever -- darts to the rim, they are rumbling into heavy traffic. A lot of lob dunks evaporate.

Doncic has seen many variants of this scheme over many years. He and the Mavericks know the counters. Washington can pop for 3s. They can run sideline pick-and-rolls to stretch Boston's defense. If Boston's centers drop back against any Doncic-Washington or Doncic-Jones pick-and-roll, that opens up an entire subset of Doncic's game -- floaters, step-back 3s, those prodding deceleration dribbles that clear space for midrangers.

The Celtics are loath to double-team. They prefer to keep their big men back on the pick-and-roll -- allowing perimeter defenders to stay home on shooters. Lots of Dallas opponents enter games with those same tenets. One quarter jousting with Doncic, and they rethink everything.

Doncic is also a genius at coaxing the very switches these matchup gambits are designed to avoid. You can put your lumbering bigs wherever you want; Doncic will find them, draw them out and lure them into one-on-one matchups they can't win. The only sustained success the Cavaliers and Pacers had on offense against Boston -- and it didn't last long -- was when Mitchell, Haliburton and Pascal Siakam attacked Horford and Luke Kornet on switches. Doncic resides in another stratosphere.

Boston will have to adapt and adjust within each game.

Porzingis' health looms as a major wild card. Boston's playoff opponents have hit a laughably bad 25% on corner 3s. Boston under Udoka and now Joe Mazzulla has made an art form of redistributing opponent triples away from the short corners, but a percentage so bad cannot sustain for long.

Meanwhile, those same opponents made 70.6% of their attempts in the restricted area. That would have ranked 28th among defenses in the regular season, per Cleaning The Glass. Boston has done well to limit opponent attempts at the basket, but that owes in part to its specific slate of opponents and the injuries those teams suffered.

What if the corner 3s start falling and Boston can't tighten up at the rim? Doncic is one of the greatest ever at creating corner 3s for teammates; the Mavericks led the league in corner 3 attempts. Porzingis, meanwhile, holds the key to cinching up Boston's basket protection.