A Boston Celtics Mailbag

Answering some questions as the playoffs draw closer

Happy Monday!

It’s Mailbag time again :)

Let’s dive in.

✉️ Rui Monteiro Mascarenhas asks: I saw somewhere that our starting 5 has a not so good net rating when playing together (firstly, is that accurate? and second is that because of the small sample size, and trying to get KP to have his sea legs under him ahead of the playoffs?). Or is that an indication that KP should come off the bench? Cheers

🗣️ My response: Rui! My guy! Hope all is well! Let’s chunk this question into two parts. First, let’s look at how the core five are performing on the floor together.

The five-man lineup of Jrue Holiday, Derrick White, Jaylen Brown, Jayson Tatum and Kristaps Porizngis is -2.2 points per 100 possessions. Their biggest issue is on offense (shockingly), with the team stagnating to 112.5 points scored per 100.

For reference, when you slot Horford into Porzingis’s place and keep everything else the same, the Celtics are +18.5 points per 100. There is a slight caveat to this, though. The lineup with Porzingis at the five has seen 710 possessions, while there are just 542 with Horford. Not a massive difference in sample size, but it's a large enough one that it should at least be mentioned.

Still, it’s worth noting that out of all high-usage lineups, the ‘core five’ is the only one with a negative points differential (net rating).

Of course, there are countless more iterations of how the Celtics have lined up, but the ones in the screenshot above are the highest usage, meaning we at least have the bare minimum of a 100 possession sample size.

So, to answer part 1 of your question, yes, sir, it’s true, on paper, the ‘core five’ is underperforming. However, how many of those possessions have come with Porzingis working his way back to fitness? What about Holiday? How many times has Brown played with a knee issue?

The fact is, the Celtics have seldom been healthy this season. As such, it’s hard to judge the true impact of the primary core when on the floor together. I do think that, judging by the game film, things are starting to level out. And, considering how minimal a -2.2 deficit is per 100 possession, we could see that unit bring their netrating to 0 or even to a +0.5 by the end of the season — wishful thinking, maybe?

Either way, I think that is’ fair to assume the Celtics are still better with Porzingis in the rotation than not. And that’s where I’ll lean into the second part of your question.

Porzingis is a true game-changer for Boston. Bringing him off the bench when he is healthy makes no sense. I get that Horford is having a solid year, and the Luke Kornet has been brilliant this season — but neither of them is Porzingis. Neither brings what he does to the table.

Moving Porzingis to the bench would mean forcing Mazzulla to rebuild his rotations on the fly. The knock-on effects there, this late in the season, could prove to be problematic. I’m also a big believer in having your best players start games, and Porzingis is, without a doubt, one of Boston’s best players.

I do get the idea here — especially when looking at the NetRating of the ‘core 5,’ but for me, once the playoffs start, things should click into place, assuming everyone is, and stays, healthy.

✉️ Rob asks: With all the 2nd apron/trade junior articles recently, with people calling it doom and gloom, are we really that much worse when Jrue isn't playing? Both from a numbers and film standpoint, is Jrue really that irreplaceable? My take is that we'll be fine. Sam, Al, or Luke can easily slot in (depending on need), and we'd put up comparable numbers. What’s your take?

🗣️ My response: The Celtics are +7.2 points per 100 possessions better with Holiday on the floor. His versatility on both sides of the floor is a core component to Mazzulla’s overall gameplan. Holiday can be your screener, your secondary scorer, primary playmaker, dunker spot floor spacer, or anything in between. He can also be your point-of-attack defender, cross-matching guard, off-ball menace, helper, low man, sink man, or once again, anything in between.

All this is to say, I think a lot of Holiday’s impact often goes unseen. It’s the little things.

It’s the knowing when to peel switch.

It’s the ability to cross-match onto a big and instantly switch onto a ball-handler.

And it’s the ability to operate as a connector, despite being good enough to be a top-three option on offense.

I think Jrue is a highly valuable member of the rotation. His versatility, experience, leadership and willingness to plug gaps make him the type of glue guy every contending team needs. Outside of Tatum and possibly Brown, I don’t think anyone on the roster is irreplaceable.

However, I would caution that the three names you mentioned above are all candidates who could leave in the summer. Horford is hitting unrestricted free agency, so is Kornet, and Hauser has been floated as a trade chip due to the $80—$90 million in luxury taxes his contract is set to incur.

I would prefer a Holiday is on the Celtics for the foreseeable future. At least until the summer. But it is worth noting that Boston is 13-4 without Holiday in the rotation this season. So, clearly, they can still win without him — whether that is true during the playoffs is a question I would rather not know the answer to.

✉️ Chris Figee asks: I am somewhat surprised to see that Joe was starting with the core 5 against the Spurs. Guess is trading off injury risk/fatigue against “finding the groove” between the 5 of them and spending more time on the floor together (building on Rui’s point, I guess)

🗣️ My response: We’re at the point in the season where you’re either going to start resting guys or start ramping things up. Considering the number of games this Celtics team has been without its top rotation, I would assume Mazzulla is trying to find a middle ground.

We’ve already seen that he’s starting to open up his playbook a little bit more. So, it stands to reason that he’s using these games, regardless of opponent, to help his primary rotation rediscover some rhythm together. I do, however, get your point regarding the risk of injury, especially in the case of Tatum (ankle), Brown (knee), and Holiday (everything), but at the same time, those risks aren’t going anywhere.

The nature of the NBA is that injuries are part of the game. One of the truest sayings is that the healthiest team usually makes it to the NBA Finals. The Celtics are either going to stay healthy, or they’re not. But allowing the rotation to stagnate a little with consistent rest is just as dangerous. You need everyone at their best, both individually and collectively — it’s the collective that I would assume Mazzulla is working on.

I like the idea of staggering guys in terms of game players, but honestly, I’m not sure how many games we see that happen, if any.

That wraps us up for today. The Celtics face the Taylor Jenkins-less Memphis Grizzlies later in the day. I’ll be here tomorrow, as usual. And as always, I appreciate everyone who reads, interacts, is part of the Substack chat (if you’re not, download the app and get involved!), and supports this newsletter. You’re all GOATS in my mind!