Second Round Showdown: Previewing the Boston Celtics

After a thorough handling of the Detroit Pistons in the first round, the Milwaukee Bucks will prepare to show down against the Boston Celtics in the conference semifinals. Like the Bucks, Boston swept the Indiana Pacers, though not in as dominant fashion. Still, winning tough games against a scrappy Indiana team (by an average of 7.5 points) is yet another indicator that things are coming together at the right time for the Celtics.

Despite their status as the 4th seed in the East, Boston boasts talent that can rival most of their NBA peers. Last year’s scrappy squad had a legitimate shot at making the NBA Finals, and in addition to Jayson Tatum, Al Horford, Jaylen Brown, Marcus Morris, and Terry Rozier, Boston has a healthy Kyrie Irving (who didn’t play in last year’s playoff series) and a not-complete-but-still-competent version of Gordon Hayward (who also didn’t play last postseason). Marcus Smart may be a notable absence, but the Boston Celtics are not short on ability.

All this said, Celtics fans (and possibly some Bucks fans) will point to the “they’re peaking in the playoffs!” cliché as proof that Boston is predestined to return to the Eastern Conference Finals. However, this ignores the fact that the Milwaukee Bucks are not the Indiana Pacers. Malcolm Brogdon missing time is not the same on this team as Victor Oladipo missing time for the Pacers, and Brogdon is expected back sometime soon. Milwaukee has an MVP frontrunner in Giannis Antetokounmpo, a motivated-to-make-up-for-last-year Eric Bledsoe, and human torch Khris Middleton, and they’re flanked by a slew of role players who do their jobs well.

Furthermore, while the Celtics may be peaking...it’s debatable whether their peak is as high as the Bucks’ plateau. Milwaukee went through a bit of a lull way back in December, but ever since they’ve simply been a basketball buzzsaw. They didn’t peak for the playoffs because they were already playing at an elite level. The Bucks beat bad teams, by a lot. The Bucks beat mediocre teams, usually by a lot. And the Bucks beat good, even great teams, and often enough by a lot!

So how should Bucks fans approach this series? Winning your first playoff matchup in two decades is exciting, but should not fuel false confidence. This second round will be a challenge, no matter how you slice it, and the best place to start is with the regular season series between these two teams, and determine what they can tell us about how the Bucks and Celtics stack up. Here are the links to each game’s Rapid Recap, detailing the quick reaction to Milwaukee’s 2-1 season series vs. the Celtics.

November 1, 2018: Boston 117, Milwaukee 113 – NBA.com box score

December 21, 2018: Milwaukee 120, Boston 107 – NBA.com box score

February 21, 2019: Milwaukee 98, Boston 97 – NBA.com box score

What can we learn from these games? I went through everything and ended up with three big takeaways:

The Celtics’ lone win is the definition of an “outlier game.”

This is not Milwaukee homerism, or an effort to feed into the “Nobahdy believes in Bahston!” sentiment we’re sure to see on Twitter later this week. Take a look at the team summaries from the box score:

The Celtics made TWENTY FOUR three pointers (on 55 attempts), which set a new franchise record for makes. Teams rarely hit 43% of their threes while taking nearly 60% (0.598, to be precise) of their shots from behind the arc, and Boston is no exception; on the season, the Celtics averaged 12.6 makes on 34.5 attempts (which is 36.5%, over six points below their mark in that game), with a year-long 3PAr of 0.381 (roughly twenty points below their mark in this game). That’s the beauty of playing the variance game; sometimes you can simply shoot your way to victory.

But not only were the Celtics remarkably hot from downtown, but the Bucks were remarkably cold. Making only 9 of their 29 three point attempts (31.0%), Milwaukee was four points below their season-average for accuracy, and eight points below for frequency (season 3PAr of 0.419, game 3PAr of only 0.341). Given how well the Bucks fared up close (margin of +40 in points in the paint) in this game and the fact that Boston only won by 4, Milwaukee could have easily won this matchup if either team shot the three ball closer to their expected averages. This bodes well for the Bucks.

“Outlier game” aside, Boston is going to shoot threes...but their overall FG% may suffer.

Of all the teams who seek to take down Milwaukee, Boston’s approach to solving Mike Budenholzer’s zone drop defense is one of the most promising. In the zone drop, the center (whether it’s Brook Lopez, Ersan Ilyasova, or sometimes Nikola Mirotic or Giannis) will sag far off from the screening action while the ball defender (usually a wing or a guard) fights through (over more often than under) the screen to keep the ball handler from taking a high-value shot. Unless the ball handler is an exceptional pull-up three-point shooter (which Kyrie Irving is), they will either pass to a teammate or dribble inside the arc...where the decision becomes either challenging the big man at the rim or taking a lower-value jump shot (the dreaded long two).

Kyrie’s wizardry aside, the hole that the offense can exploit is with the screener, often a big and often on the wing or at the top of the key. Bigs who can shoot the three find themselves wide open (Lopez and Ilyasova obviously struggle to cover ground when hanging back in the paint), so if the pick-and-roll becomes a pick-and-pop, all the screener needs to do is take the open jumper. Al Horford (3PT%: 36.0) can do this, as well as dribble or pass to another opening. Ditto for Aron Baynes (3PT%: 34.4) and Daniel Theis (3PT%: 38.8).

This dynamic has been how Milwaukee achieved an elite defensive rating (105.2, first per basketball-reference.com): they allow a lot of threes (36.3 attempts per game), but they’re usually successful funneling those shots to worse/less frequent shooters. But the Boston Celtics have a number of capable shooters (eight players at 36.0% or higher), and they were not shy taking open threes in the regular season against Milwaukee. In those three games, the Celtics averaged a 3PAr of 0.486, over ten points (and nearly 30% higher) than their regular average (0.381). This is as red of a flag that you’ll find if you’re rooting for Milwaukee.

But if the Celtics are going to live by the three, games 2 and 3 of the regular season show how they could die by the three. Despite their scorching performance in game 1, they averaged only 36.0% from deep (close to their season average of 36.5%) across all three games, because they shot only 29.4% and 35.0% in games 2 and 3. This, combined with their lack of interest in getting to the rim (of their main contributors, Jaylen Brown has the highest percentage of shots from 0-3 feet at 0.314) and low free throw rate (0.215 as a team) is what keeps the Boston offense from feeling consistently potent. Indeed, in games 2 and 3, Boston’s overall field goal percentages were sub-40 (0.385 and 0.382)

Milwaukee’s best path to victory is to control the glass.

If game 1 included a huge shooting disparity on both sides, and games 2 and 3 were more within expected ranges, what other aspects will decide the series? You could look at how well Boston protects the ball (averaging 12.8 turnovers per game, but only 8.0 turnovers in three games against Milwaukee), which limits the Bucks’ opportunities for transition scoring and aligns poorly with the Bucks’ pedestrian turnover creation performance (averaging 7.5 steals per game, but only 5.3 in three games against Boston). You could also recognize Boston’s strong defense (DRtg of 107.8, 7th in the NBA) and deliberate pace (99.6, 16th in the NBA) as a path towards grinding games to a halt and controlling the tempo. There are other details, too, where one team’s weakness is the other team’s opportunity.

But more than anything, Milwaukee’s strong rebounding ability is the key to swinging the series in their favor. At 49.7 total rebounds per game and a league-leading defensive rebound rate of 80.3%, the Bucks have a massive edge over Boston on this front (average total rebounds per game: 44.5, 22nd in the NBA; defensive rebound rate: 77.0%, 18th in the NBA).

In their lone loss, Milwaukee only bested the Celtics on the boards by a margin of +3 (45-42), in no small part because of how many shots Boston made, but also because their high volume of three-point attempts from bigs (28 combined attempts from Horford, Baynes, Morris, and Semi Ojeleye) pulled the Bucks’ big men away from the rim, and therefore away from possible rebounds. In games 2 and 3, though, this wasn’t the case. The Bucks bludgeoned Boston on the boards in their December blowout (55-36, +19 rebounding margin), and bested the Celtics by only five (55-50) in February, which was decided in the final moments.

The Bucks need to be themselves in this series against the Celtics. They’re good, but Milwaukee is better. If Coach Bud, Giannis, and the rest of the team can simply execute on the aspects of their scheme that led them to 60 wins and the top seed in the playoffs, they should be able to withstand Boston’s best efforts and come out on top...but much like the Detroit Pistons, the Celtics will not go down without a fight.