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New NBA Championship Prediction Model and NBA 2021 Playoffs Preview

By Zach Hales, CouchGM on May 18, 2021

CouchGM’s NBA Championship prediction model has been updated ahead of the playoffs.

Two months ago at the All-Star break, we took a look at how each team was doing and created a model to determine which teams were most likely to win the NBA Finals. We also gave a guarantee: the 2021 NBA Champion would be one of the Jazz, Bucks, Clippers, Suns, Nuggets, Nets, and Lakers.

I won’t lie, watching the Philadelphia 76ers and Joel Embiid post-All-Star Break had me nervous about that guarantee, but I’ll stick with it. I’ll even eliminate the Nuggets and give a top-6: Jazz, Bucks, Clippers, Suns, Nets, and Lakers. I’m not brave enough to eliminate anyone else yet.

Since then, I’ve updated that model to now give a probability of winning the NBA Championship. The model is based on the criteria for winning the NBA Championship that we previously established. It now also includes seeding (6 of the last 8 champions were 1-seeds and the other 2 were 2-seeds). Here’s a look at the criteria, as a reminder.

The table below shows the new probabilities, sorted by decreasing odds as of the end of the season, along with the change from the All-Star break. Note: the rankings at the All-Star Break are a little different here than in the previous post since the model has been updated to include standings/seeding.

Surprising big risers include the Portland Trailblazers, who made the second biggest jump after the All-Star break, behind only the LA Clippers. The Jazz are still comfortable favorites, but the Clippers closed the gap significantly.

In the East, the Bucks are the biggest faller, making the Nets the overwhelming favorite. The Sixers also rose significantly, making a jump into the top-4 (still a little nervous about leaving them out of my guarantee…).

This model also gives much better odds to the lower-seeded teams than other models. Fivethirtyeight’s model only has 9 teams with 1% or greater odds and two teams with >20%. The Ringer has 11 with 1% or greater and gives the favorite Jazz a whopping 44%. Everyone has at least 1% in our model and nobody is higher than Utah’s ~17%. So we’re a little more generous to the little guys and more conservative on the favorites. Remember: all models are wrong, but some are useful.

Overall, the Jazz, Clippers, and Nets are the clear top-3.

Here’s how the model sees the play-in games turning out in the East.

The 7 vs 8 and 9 vs 10 go as expected with the higher seed winning, but in the third game (7 v 8 loser against 9 v 10 winner), our model expects the Pacers to beat the Wizards. Not sure I agree with that one, but it could go either way. They have identical 34-38 records.

And in the West.

All chalk here. I think the Lakers do probably beat the Warriors, but as a Suns fan I’m secretly hoping the Warriors win since I think the Suns will have an easier time with the Warriors in the first round than the Lakers. I’m also interested to see how the Spurs do. They have never missed the playoffs in consecutive years. Do they have to win and reach the 1 vs 8 matchup to keep that streak alive, or does making it into the play-in game count? Our model isn’t very optimistic that they’ll make it past the play-in.

Moving on to the first round matchups in the East (assuming the Celtics get the 7-seed and the Pacers the 8-seed).

And in the West (assuming the Lakers get the 7-seed and the Warriors the 8-seed).

It gets more interesting in the West, though, with our model predicting that the Blazers will beat the Nuggets. This wouldn’t surprise me at all. The Nuggets have been good since acquiring Aaron Gordon even without Jamal Murray, but remember that in the playoffs it’s Dame Time all the time. I take Lillard and the Blazers.

The Suns-Lakers series has me a little nervous as a Suns fan. I actually like the Suns’ chances against everyone in the West except for the LA teams (3-0 against Portland, 3-0 against Utah, 3-0 against Dallas, 2-1 against Golden State, only 1-2 against Denver but the two losses were early in the year and in OT and the Suns were much better in close games later in the season).

The model will be updated with the completion of each round. For now, the Jazz are the frontrunner. But as I’ve said before: LeBron still reigns and it feels wrong to bet against him, even if the Lakers are only the 7-seed.

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