Inside the Boston Celtics, Milwaukee Bucks Chess Match

This article is a facsimile of an earlier publication on The Basketball Writers (TBW), which recently closed its doors.

Despite a first-round sweep of the Indiana Pacers, the Boston Celtics weren't firmly blowing their adversaries out of the water. Each game was decided in the final minutes.

Yet, the prevailing "talking heads" takeaway is that the Celtics' chemistry issues are now fixed and they look like themselves.

Really? A four-game sweep of a banged-up, easy-to-guard Pacers squad is restoring our faith in the season's most disappointing team?

Their biggest test lies ahead, squaring off in the Eastern Conference Semifinals with the Milwaukee Bucks, the league's top team through the regular season and one featuring MVP candidate Giannis Antetokounmpo. Even if the Celtics have found their swagger, the task ahead of them is still a tall one.
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The question isn't so much "are the Celtics capable of beating Milwaukee?" as much as "can they consistently play well enough in a playoff series to do so?"

That word—consistency—has been the missing link all tantalizingly frustrating season long. The postseason is a series of tactical battles where teams try to take away their opponent's strength while limiting their own vulnerabilities. In order to beat Milwaukee, the Celtics must get the game played their way, and do so before the Bucks can solve their formula. Make no mistake, the Celtics may be the team best built to foil Milwaukee in the Eastern Conference.
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But that doesn't mean they're likely to do so.

Milwaukee's ball

During their most recent regular-season matchup, the Celtics found ways to match up with the Bucks' shooting frontcourt—by far their most unique offensive attribute. From the tip, Al Horford was positioned on Giannis, with Marcus Morris drawing the assignment on stretch-5 Brook Lopez. That allowed the Celtics to switch occasional pick-and-pops with Lopez and neutralize his threat. Since Morris is an agile on-ball defender, the C's did not yield the paint to isolation drives.
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Horford did a great job on Giannis, keeping him in front and using length and angles to wisely guard the Greek Freak. But Horford was far from alone on this assignment. The Celts would routinely send one of their defenders to jump Giannis as he engaged in his dribble move:

The result was a timid and tentative Antetokounmpo, who would force switches and mismatches onto Kyrie Irving or other less-solid defenders, but then fail to properly or aggressively attack them.

Watch how the Celtics guarded him in their most recent matchup on high ball screens—Milwaukee's desired action to force a switch. Several times they'd have the weak-side help rotate towards him as he drove or rolled, forcing Giannis to finish over multiple defenders at the rim. He became timid to attack those mismatches and was very passive, even when he got Kyrie on him.
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The Celtics swarmed from the weak-side, and that may have been enough to get Giannis jump shooting or deferring to others:

What should worry Celtics faithful? Transition defense and cross-matching.

Coaches and pundits that discuss strategy tend to focus on the half-court execution, areas where the table is nicely set and coaches have a great deal of tactical control. But the league's best teams shoot less than 50 percent from the field, meaning more than half of the game is spent with defenses lacking that typical, neatly-defined organization.

When a player is forced to defend someone that isn't their assigned matchup, we call that cross-matching. For instance, if Giannis gets the ball and sprints down the right wing, Kyrie Irving may be the only option to prevent a layup. He steps up to Giannis and now must guard him in the half-court for at least a portion of the possession.

The Bucks are great at keeping those cross-matches and exploiting them (at least when Giannis is aggressive against them) because he is versatile enough to mismatch any type of player that shouldn't be guarding him.

Milwaukee's free-flowing motion is the perfect match for a smart player like Antetokounmpo to find his bread and butter. We could discuss tactical adjustments until we're blue in the face, but none of it matters if the Bucks dominate during this part of the game and are able to pick on Kyrie.
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The Celtics have always worked hard to cover up for Irving's deficiencies and even found ways to do so against the Bucks. They rotate so well around Kyrie and Terry Rozier, and are so fast at switching to neutralize mismatches:

Boston's Ball

Milwaukee's defense has been consistently strong all season despite the missing presence of a vertical rim protector. They get by with the supreme length of their wings and by having elite perimeter defenders like Antetokounmpo and Bledsoe.

First-year coach Mike Budenholzer has protected his bigs by running a conservative drop against ball screens, a method that allows Lopez to rarely venture to the three-point line. His length and understanding of angles allow him to be effective. Ersan Ilyasova, an undersized 5-man with no leaping ability, is one of the league's best charge-takers. Those two will sit back and let the Celtics come to them, knowing they can effectively defend the interior despite not being a threat to block shots.

Playing through Al Horford and the pick-and-pop has been Boston's prized counter to such a scheme. There's little way to cover both the top of the key after a pick-and-pop and protect the rim.
By dropping back, the Bucks are picking their poison and daring Horford to bomb away. That's the shot they'll live with, as evidenced by the amount of top-of-the-key threes the Celtics took against them during the regular season.
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Horford, Marcus Morris and even Daniel Theis got plenty of good looks:

Daring Horford, the perfect frontcourt facilitator and team-first player, to become a top offensive option is a strategy that's common against Boston. The Celtics are 8-9 this season when he takes 13 or more shots, and 2-5 when he takes six or more treys. That begs the question: Are the Celtics offensively built to beat a team like this?

Big Al tried to find other avenues to exploit Milwaukee other than settling for jumpers. When he's driving and facilitating after pops, the Celtics are a much more dynamic offensive group. That's why they're 8-2 when he has seven or more assists.
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The other option is to put another playmaker in the screening spot. So long as the Celtics can force a hedge with a smaller wing, the throwback would be into the hands of a playmaker like Jayson Tatum or Gordon Hayward, who are much more equipped to be scorers when they put it on the floor:

Their two best and most consistent perimeter scorers, Tatum and Irving are effective through isolation and downhill drives. The length of the Bucks' backcourt, combined with their overall defensive aptitude, could slow that attack, however.

If the pick-and-pop to Horford isn't a threat the Celtics can score with efficiently, that only adds more stress to Boston's defense.

The elephant in the room remains the expected absence of Marcus Smart, who suffered an oblique injury during the first week of April.

Expected to be sidelined for the first two rounds of the postseason, Smart is an ideal defender for Giannis or sweet-shooting wing Khris Middleton due to his ability to simultaneously contain them off the bounce and neutralize them in the post.

An effective strategy against Giannis as a ball handler is to put a tough, quick guard on him that can undercut his dribble. Since Giannis is so tall, a normal dribble that comes to his waist is easier to be poked away by a six-foot guard.
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Smart was an instinctual off-ball defender that could impact the series with his aggression and willingness to disrupt everything. He's got a nose for the ball and can help protect the Celtics from isolations against switches by perfectly timing his gambles:

Without the luxury of Smart, the Celtics likely will throw all their weight behind Horford and Jaylen Brown to defend Milwaukee's two best players. Their top defender is gone, stretching their backcourt thin while removing the security blanket that served as a protector for Kyrie Irving.

Now might be the time to dust off the likes of Semi Ojeleye for a few spot minutes, going bigger on the wings instead of trying to steal some minutes with both Horford and Aron Baynes.

Both ends of the court hold great importance to the Celtics in this series. They need to effectively mitigate Antetokounmpo's damage in the half-court while preventing the Bucks' shooters from getting hot. Offensively, Horford is the key, and the more they can find ways to alleviate the burden falling on him to be a scorer, the better off they'll be.
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They have a chance in this series, but they'll need to find ways to get Horford going so he wins his matchups on both ends of the floor.