2021 NBA Playoffs Preview: First Round Model and Probabilities
The good thing about being a data guy is I can just write code for a few hours and deliver valuable insights like ‘The Philadelphia 76ers have a 23% chance at winning the championship’. While the other NBA pundits and walking encyclopedias can debate topics like ‘are the Heat a trap series for the Bucks’, I can cut straight to the point and give you the answers you want (no, they aren’t).
In this 2021 NBA playoffs preview I’ll go through a couple conclusions one can take away from the output of my Bayes Ensemble model. In particular I’ll
- Present my overall team rankings
- Give the championship probabilities for each team
- Preview each series including most likely outcomes (like, for example, ‘6ers in 4’).
Throughout these playoffs, I will be posting on our social media with updated graphics much like the ones you see in this article. So, if you haven’t yet, please be sure to use the icons on the right of this article to find our social media pages. Moreover, before each round I’ll be sure to post an update article discussing what has changed and giving more insights for the upcoming round.
If you want to skip ahead to a particular section use these links: Championship Probabilities, Sixers-Warriors, Knicks-Hawks, Bucks-Heat, Nets-Celtics, Jazz-Warriors, Clippers-Mavs, Nuggets-Blazers, Suns-Lakers.
NBA Playoffs Team Rankings
I created these rankings using my Bayes Ensemble method. If you forgot, here is a quick refresher. The Bayes Ensemble method mixes together recent game data with Vegas lines to rank teams. Using Vegas lines lets us properly weight teams like the Lakers whose recent game data doesn’t correspond well to how good they actually are. Using actual game data lets us cut through any biases and to determine actual relative quality of teams. A mixture of the two gives us data that is both based on observed games having been played and that takes into account the wisdom of the masses.
Below is the table of team rankings. Recall that the difference between two teams’ rankings is my prediction for the margin of victory on neutral court. So, for example if the Jazz (7.9) played the Bucks (7.1) in the finals, then I would predict the Jazz to win by (7.9-7.1+1.5)=2.3 points on average at home and lose by 0.7 points on average on the road.
My model – as well as all the other analytics guys – have the Jazz as the top dogs. Following closely behind, all separated by less than one point, is the 76ers, Nets, Lakers, Clippers, and Bucks in that order. Long story short: it’s going to be close, it’s going to be exciting, and if you ask me who is going to win I’ll say it’s a tossup. Below is the full table of rankings for each team in the field.
| Team | Ranking |
|---|---|
| Utah Jazz | 7.9 |
| Philadelphia 76ers | 7.8 |
| Brooklyn Nets | 7.5 |
| Los Angeles Lakers | 7.5 |
| Los Angeles Clippers | 7.2 |
| Milwaukee Bucks | 7.1 |
| Phoenix Suns | 6.9 |
| New York Knicks | 5.3 |
| Denver Nuggets | 5.2 |
| Dallas Mavericks | 5.1 |
| Portland Trail Blazers | 4.1 |
| Memphis Grizzlies | 3.1 |
| Miami Heat | 3.0 |
| Boston Celtics | 2.7 |
| Atlanta Hawks | 1.9 |
| Washington Wizards | 1.9 |
| Golden State Warriors | 1.5 |
| San Antonio Spurs | 0.1 |
| Charlotte Hornets | -1.1 |
| Indiana Pacers | -2.1 |
2021 NBA Championship Probabilities
When it comes down to it, though, equally as important as how good you are is how favorable the bracket is for you. Last year, the Lakers won the championship with very, very few losses. If you look at how the bracket played out, though, it isn’t actually that surprising. The Lakers didn’t have to play either of the other two pre-tournament title favorites: the Bucks and the Clippers. The bracket was just that good to them.
So, I went through and simulated the entire tournament 100,000 times and counted the percent of times each team won. Introducing your Data Jocks pick for 2021 NBA champion: The Philadelphia 76ers. Why? Well, first of all it helps to be the second best team in the league. More importantly, though, the Sixers crucially have a much easier second round matchup than any other of the top 3 seeds on either side. In the second round, Philly gets either the Knicks or Hawks while the Nets and Bucks get to abuse each other. The Jazz have to go through the Clippers and one of Phoenix or LAL. Most simply, the ease of the Sixers second round is enough to move them to the top spot. Below is the full list of championship probabilities:
- Top Tier (>=10%): Sixers 23%, Jazz 22%, Nets 15%, Bucks 10%
- Tier Two (5-10%): Lakers 9.2%, Clippers 8.1%, Suns 6.9%
- Tier Three (1-5%): Knicks 2.6%, Nuggets 2%
- Tier Four (<1%, in decreasing order): Mavericks, Blazers, Heat, Celtics, Warriors, Wizards, Hawks
My translation for the tiers is ‘Teams that should win’, ‘Teams that could win’, ‘Teams that would be an historical outlier if they won’, and ‘If one of these guys wins I will retire from sports analytics for good’.
Individual Series Previews
In the remainder of this article, I am going to go through each first round series and give a quick overview. I’ll try to give some perspective on the game and things to watch for, but quickly I will take a numbers-based approach. For each team I will give their probability of winning the current series. Then, I will give you the most likely outcome in terms of pure probability and the median outcome. The median outcome in this setting can most reasonably be interpreted as ‘I am 50% confident the series ends up to and including this point and I am 50% confident it ends after this point’. Lastly, I’ll give a bar graph showing the probability that the series ends in any given number of games. Perhaps the most surprising thing to me is just how many series I expect to be over in exactly 5 games. Again, I’ll be updating these graphs and this data as the first round goes on over on our social media.
Sixers-Wizards Preview
We’ll open up with our championship favorites, the Philadelphia 76ers. Here’s the thing: Philly is awesome and their route to the finals is the easiest of any team. The Nets have to go through the Bucks and the 6ers, the Bucks have to go through the Nets and the Sixers. The Jazz, Clippers, Suns, and Lakers have to go through at least of two of each other to make the finals. Philly only has to go through one top tier team.
Washington, on the other hand, is pure fun. Russell Westbrook is one of the most athletic, energetic, and exciting players to watch. Bradley Beal is a top 5 pure scorer in the league. Unfortunately, the Wizards likely just won’t have it. From a purely subjective perspective (something I try to avoid as often s possible), there is not a soul on the Wizards who can slow down Embiid. To be fair, there isn’t a soul in the NBA who can do that, but certainly this is even truer on the Wizards. Let’s see what the data says.
Sixers Winning Probability: 92%
Wizards Winning Probability: 8%
Most Likely Outcome: Sixers in 5
Median Outcome: Sixers in 5
Knicks-Hawks Preview
This is certainly one of the most exciting and anticipated matchups in the first round. The Hawks are one of the most fun Young teams out there. Perhaps one of the biggest stories is watching the should-be-winner of most improved player Julius Randle. However, as a Dayton Alum, I have to root for the Knicks on behalf of Obi Toppin – regardless of if he is good or how much he plays.
Interestingly, Vegas thinks this matchup is a complete tossup: both teams are at -110 to win the series. My model significantly disagrees. In fact, even giving home court advantage a measly 1.5 points because of the lack of full arenas, my model gives the Knicks an 80% chance of winning the series. That is a crazy big discrepancy. I don’t do much sports betting, but if I did….
Knicks Winning Probability: 80%
Hawks Winning Probability: 20%
Most Likely Outcome: Knicks in 5
Median Outcome: Knicks in 6
Bucks-Heat Preview
On paper, this series is going to be thrilling. Everybody remembers last year all too well…
Giannis had won his second straight MVP and was ready to take over for LeBron as ‘the undisputed best player in the league for the majority of his career’. But Jimmy Butler happened. And Giannis’ career trajectory cooled off a bit from the ‘to the moon’ path it was on. You just have to imagine that this thought is near the top of the Bucks’ minds.
Vegas has the Bucks at -280, fairly heavily favored. What does my model say?
Bucks Winning Percentage: 82%
Heat Winning Percentage: 18%
Most Likely Outcome: Bucks in 5
Median Outcome: Bucks in 6
Nets-Celtics Preview
Ever since I turned on ESPN after the Celtics won on Tuesday night, all I heard was one person or another previewing this game. The New York-Boston matchup is always great on its own and media will be all over it. The return of Kyrie Irving against his former team is going to be a treat. And, if you go all the way back to 2013, you’ll remember the famous Nets/Celtics trade that involved two hall of famers and three of the Nets’ first round picks.
The outcome of the 2013 trade was supposed to be this: Boston would ascend to glory with its treasure chest of assets and the Nets future was bleak. Yet, here we are with the Nets as the betting favorites to win the title and the Celtics limping in as the 7 seed. This is why we play the game.
To the numbers….Vegas has Brooklyn as -800 to win the game which is a fairly significant favorite. The implied odds here are something around a 90% chance for Brooklyn to win. My numbers agree almost exactly.
Bucks Winning Probability: 88%
Celtics Winning Probability: 12%
Most Likely Outcome: Nets in 5
Median Outcome: Nets in 5
Jazz-Grizzlies Preview
The Jazz were lucky enough to avoid the Lakers. What a reward that would have been for the one seed. While most people will say ‘the Jazz got lucky and avoided the Warriors as well’, my model doesn’t agree. Looking above at the ratings I provided, you can see that the Warriors are about 1.6 points worse in rating than the Grizzlies are.
Maybe there is something to be said for not playing against an all-time great in Steph Curry. Maybe that narrative is overblown. Either way, though, the Jazz are still heavily favored to move on after this series. My model says…
Jazz Win Probability: 88%
Grizzlies Win Probability: 12%
Most Likely Outcome: Jazz in 5
Median Outcome: Jazz in 5
Clippers-Mavericks Preview
The Clippers are extremely interesting this year. Many people – myself one of them – had the Clippers as the favorites last year before the playoffs started. They were a force. This year, though, it is unclear what has changed to make them not nearly as hyped. Sure, losing Montrezl and Lou hurts. But that much? My model doesn’t think so. The Clippers according to my model are still the 5th best team, just a touch behind the Lakers.
The Mavericks are also my pick for biggest disappointment this year. If I remember back to the beginning of the year correctly, I think I had Dallas as my dark horse pick for the 2 seed. Admittedly, I don’t really know what went wrong other than Kristaps issues and missing Seth Curry more than they realized.
Vegas has this series very heavily in favor of LAC: -450. Percentage wise, this is about 82%. My model is higher on Dallas than most (my model has been high on Dallas since the very first time I ever ran the numbers, I can’t explain it), let’s see what it says.
Clippers Win Probability: 72%
Mavericks Win Probability: 28%
Most Likely Outcome: Clippers in 5
Median Outcome: Clippers in 6
Nuggets-Blazers Preview
The Jamal Murray injury might be the biggest what-if moment of this year. The Nuggets have the likely-MVP. With Murray they had an awesome guard (don’t forget how good he was in last year’s Jazz and Lakers series). The supporting cast is great. Unfortunately, though, without Murray the consensus has to be that it is not the Nuggets year.
The Blazers are actually in a surprisingly similar situation. They have an MVP-level player in Dame. They have a near all-NBA , the sidekick sitting out (CJ). The Blazers are really good for a 6 seed. Vegas agrees, calling the series basically a tossup (Portland -115, Denver -105). What does the model say?
Nuggets Winning Probability: 62%
Blazers Winning Probability: 38%
Most Likely Outcome: Nuggets in 7
Median Outcome: Nuggets in 7
Suns-Lakers Preview
Sigh. I started writing this article halfway through the Warriors-Lakers game, so I had started writing a Suns-Warriors preview. Straight up, the Lakers looked terrible in the first half. However, at halftime something magical happened: LeBron decided Schroeder couldn’t run the offense and AD decided he didn’t suck anymore. The result…the Lakers erased a 13 point deficit in 4 minutes.
I feel so bad for the Suns. Their first time back in the playoffs for a long time and their first round matchup is Vegas’ second betting favorite to win the title from the 7 seed. Pretty unfair. This seems like another prime chance for Banana boat bro Chris Paul to have another early exit from the playoffs. (If you ask me, Chris Paul is going to get the Barkley treatment after his career. Awesome player, never made it because he played at the same time as some all-time greats).
Almost certainly this will be the best first round series of all time. ALMOST CERTAINLY everyone is going to pick the Suns to lose this series, Vegas has the Lakers at -220. But what does the model say? Things are a bit closer…
Suns Winning Probability: 44%
Lakers Winning Probability: 56%
Most Likely Outcome: Lakers in 6
Median Outcome: Lakers in 7
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