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Data or drivel: The numbers of Boston’s first 30 games

Figuring out which stats are meaningful and which are not can be a tough chore

NBA: Boston Celtics at Cleveland Cavaliers David Richard-USA TODAY Sports

A week is a really, really long time.

Just one week ago, the Celtics were reeling from a difficult 1-4 road trip, returning to Boston and hoping to have Jaylen Brown back in the lineup. The conclusion of the west coast trip also signified the one-third mark of the season for Boston, and we celebrated the occasion with a statistical dive into their start.

Since that point, the Celtics have returned to TD Garden gone 2-1 with trouncings of the Milwaukee Bucks and New York Knicks and a tight loss to the Golden State Warriors. Seemingly every member of the team has gone into COVID protocols, and future games are in jeopardy ahead of the holiday. With so many non-basketball items sliding to the top of the worry list, diagnosing the team’s basketball issues feels less important. Daily availability and injury reports is like a game of whack-a-mole... as soon as one absence gets rectified, another takes its place.

Regardless, whenever there’s a scoreboard, our goal should be to come out on top. The Celtics can and should spend a pause looking to get some answers for how to play better, or at least more consistently.

Perhaps a look at those numbers we mentioned last week is a good place to start. In that spirit, we’ll play a little bit of what we call “data or drivel” with the numbers of Boston’s first-third, figuring out which are indicative of who they are and which are mere coincidence.

NBA: Milwaukee Bucks at Boston Celtics Paul Rutherford-USA TODAY Sports

1. The Celtics are 2nd in the NBA with 10 percent of their half-court offensive possessions ending in isolation

This one seems like it might be important...

By and large, teams that are heavily isolation-driven are filled with star players. The Celtics meet that criteria with Jayson Tatum and Jaylen Brown, but there’s an issue with how the rest of the roster is built around them: there aren’t enough guys who put pressure on the rim. So when Tatum and Brown are going one-on-one for long stretches and not putting their head down or making defenses collapse, the C’s become a jump-shooting team.

Baked into that number being so high was our second statistic: that Jayson Tatum is third in the NBA in isolations per game. That’s to be expected for how much offensive heavy-lifting he has to do.

Here’s the scary part: Brown isn’t even second on the team in isolation attempts. That distinction belongs to Dennis Schroder with 81 isolation possessions, according to Synergy. That’s akin to three per game, which would put him 20th in the NBA in isolation frequency. Yikes.

Here’s why that’s a big deal. According to Synergy league tracking data, isolations are the play type they measure with the second-lowest assist rate (offensive rebounds is lowest, for obvious reasons). When the C’s are in isolation mode, the ball simply moves less. So a lack of ball movement plus a lack of rim pressure... not hard to figure out that’s not an ideal way to play the game.

We classify this as data due to its relation to how the Celtics play. They are a jump-shooting team, and a team reliant on their best offensive options to create, not scheme, system or balance.

Toronto Raptors v Boston Celtics Photo by Brian Babineau/NBAE via Getty Images

3. With 81 assists, Al Horford is fourth in the NBA among centers

While we love big Al, this is probably closer to drivel than anything else. First off, the phrasing and classification of a “center” is very ill-fitting for how the game is played. Players who are above Horford on this list but aren’t classified as centers include Draymond Green and Julius Randle.

There’s also a class system when it comes to statistics. At the bottom are what we call raw stats, the totals like points, rebounds or assists. Those who play the most rack up the largest numbers. Just above that tier is the middle-class of statistics, the “per game” stats. They attempt to show a little more, accounting for injuries and absences as opposed to overall tallies. The top shelf are per minute or per possession stats, which seek to measure impact when time and opportunity are relatively equal.

Horford would be fifth in per game stats among centers, and sixth in per-36 minute rates. Still impressive, but not quite as elite as our cherrypicked metrics would indicate.

Boston Celtics v Phoenix Suns Photo by Christian Petersen/Getty Images

4. Of the 89 players in the NBA with at least 4.8 3-point attempts per game, Marcus Smart is 88th in shooting percentage (28%)

Since posting our article last Monday, Smart has gone 2-9 from deep, thus lowering his 3-point percentage on the season.

Smart is a career 31.7% shooter from deep, so he is far from a great option there. But Smart hasn’t been below 30% from deep since 2017, or below 33% since 2018. This has been a pretty impactful fall-off for Smart.

How much is it costing the Celtics? Based on his attempt rate (4.6 threes per game), making 33% of his treys would add 0.3 makes per game, which is worth basically one point. It may not sound like that much, but that’s a pretty big swing based on jump shooting alone. Smart’s volume is high enough that a five percentage-point swing in his shooting is worth one point per game. This is definitely data to go back to when looking to explain the C’s relative offensive struggles.

Boston Celtics vs Milwaukee Bucks Staff Photo By Matt Stone/MediaNews Group/Boston Herald

5. The Celtics force their opponents to take a league-high 12.7% of their possessions into the final four seconds of the shot clock

While the data drawer is open, shove this one in as well. As we shift to the defense, it’s worth noting that the C’s are now down to 14th in half-court defensive rating. An up-and-down season can likely be traced to their defense. An elite stretch of defensive play was ruined on their West Coast road trip:

Start of the season (7 games): 119.7 points per game surrendered
Middle portion (15 games): 97.6 points
Since the start of their West Coast road trip (8 games): 114.6 points

When the Celts were at their best defensively, it heavily coincided with forcing late-clock possessions, which are defined as having a shot or turnover take place in the final four seconds of the clock. Here’s how those numbers stack up over those streaks:

Last 8 games = 11.9 late-clock possessions forced per game
Previous 15 games = 14.5 late-clock possessions forced per game

The question becomes whether there’s a correlation here or if this is causation: if the Celtics forcing more lengthy possessions is the reason their defense allowed fewer points. Considering the average NBA team scores 0.83 points per possession (PPP) at the end of the clock and 0.95 PPP in the half-court overall, it’s more than likely the source of their success than a simple coincidence.

6. When Enes Freedom is on the floor, the Celtics are 16.3 points per 100 possessions better than when he’s off

This one is drivel. Individual plus-minus stats are largely irrelevant and impacted too much by the variables at play. For example, Kanter’s minutes largely coincide with Jayson Tatum’s against other bench units, where Tatum tends to feast. Pay no attention to that individual plus-minus behind the curtain!

Milwaukee Bucks Vs Boston Celtics At TD Garden Photo by Barry Chin/The Boston Globe via Getty Images

7. In 181 minutes together, Timelord and Horford two-man frontcourt combination have a -1.9 net rating per 100 possessions

If one-man plus-minus ratings are garbage, two-man combinations are... slightly less garbage. However, these metrics can be more reliable when utilized to judge starting groups and lineups who face other teams’ best units. The Horford and Williams timeshare is about a commitment to a different style of play, a bigger group on the floor.

Instead of looking at their work together, perhaps the best way to judge their potency is to see how our best players perform when they have one of Horford/Williams, neither and then both.

Trying to find a common link on the Williams and Horford pairing from this data is challenging. The C’s seem to be best when Timelord is on the floor next to Tatum and Brown, but nothing is definitive. We like stats who give clear feedback, not confusing or multi-layered lineup analysis that needs to be sifted through with multiple grains of salt.

Don’t let the fancy charts or official-sounding stats fool you. This dose of lineup metric is a little bit of drivel.

10. The Celtics are 1-9 when they give up 110 points or more in regulation

In the three games since we wrote our first article on stats, the Celtics are 2-1. The two wins? Opponents scored fewer than 110. The one loss? You guessed it.

The stat isn’t really indicative of a cause; there’s no real reason why they give up those points in those games that we can infer from the stat. All it does is give us a magic number, based on the pace and style of play the Celtics (and their opponents) have, to aim for every night. Neither data nor drivel, this one is simply the litmus test that we can use for the C’s moving forward.

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