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We Built A WNBA Prediction Model For The 2021 Season

When last we saw the WNBA’s best players on the court, the Seattle Storm were capping off their undefeated postseason with a championship sweep of the Las Vegas Aces in the league’s Bradenton, Florida-based bubble. The 2021 season, which tips off Friday, should be somewhat more normal than 2020 — the emotionally draining experience of the “wubble” is a thing of the past, after all. But some things will be the same. Between the COVID-19 pandemic and a break in July and August for the Tokyo Olympics, the WNBA schedule will be shorter than usual (32 games this time around). And the Storm are favorites to end 2021 the same way they did 2020, celebrating a title.

At least, that’s according to our new WNBA prediction model, which we’re rolling out today in anticipation of the new season. You can read more about how it works, but the basics are similar to our other forecast models: We’re using Elo ratings to measure every team’s strength over time (based on game results), and we simulate the schedule thousands of times to track how often each team makes the playoffs and, ultimately, wins the championship.

We introduced our WNBA Elo ratings last spring, but this year we have a dashboard where you can track them in real time throughout the season. (It can even tell you which games to watch based on the quality of the matchup, its importance or both!) If we’d had that up and running last year, here’s what each team’s trajectory would have looked like over the course of the 2020 season:

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Coming off a so-so season without many of its best players (including Breanna Stewart and Sue Bird), Seattle worked back to full strength in 2020 and was playing at a historically high level by the end of the WNBA Finals. In addition to going 24-4 across the regular season and playoffs — tying the 2014 Mercury for the fourth-best single-season winning percentage (.857) in league history — the Storm’s final Elo rating of 1741 ranked second only to the dynasty-era 2000 Houston Comets for the highest peak of any WNBA team ever.

Since the WNBA has a lot of season-to-season parity, we have to regress Elo ratings significantly to the mean when setting the preseason ratings for the following year.<a class="espn-footnote-link" data-footnote-id="4" href="#fn-4" data-footnote-content=’

Our WNBA model blends a team’s previous end-of-year Elo rating 50-50 with a league-average rating when setting preseason Elo. By comparison, in baseball and football we revert team ratings to the mean by only one-third between seasons.

‘>4 So Seattle dropped down to a rating of 1621 when we got the team ratings ready for 2021. But that still gives the Storm a 31 percent probability of winning their second-straight title (and third in four seasons) according to our model:

The Storm lead our inaugural WNBA forecast

Predicted records and chance to advance in the playoffs for 2021 WNBA teams, based on Elo simulations

Regular Season
Chance to…
Team
Elo Rating
Wins
Losses
PPG Diff
Make Playoffs
Make Finals
Win Title
Storm
1621
21
11
+5.1
96%
51%
31%
Aces
1551
18
14
+2.1
84
26
13
Sun
1546
18
14
+2.0
83
25
12
Sparks
1525
17
15
+0.9
77
19
9
Lynx
1521
17
15
+0.9
77
18
8
Mercury
1513
17
15
+0.6
74
16
7
Sky
1500
16
16
0.0
70
14
6
Mystics
1497
16
16
-0.1
68
13
5
Wings
1460
14
18
-1.8
53
7
3
Dream
1447
14
18
-2.2
49
6
2
Fever
1434
13
19
-2.8
43
5
2
Liberty
1385
11
21
-4.8
26
2
<1

Forecast is based on 100,000 simulations of the regular season and playoffs.

Plenty could get in the Storm’s way, however. Seattle remade its roster heavily in the offseason, losing Alysha Clark in free agency to the Washington Mystics and trading Natasha Howard and Sami Whitcomb — all of whom had played very well in 2020 — to the New York Liberty in a flurry of moves that saw the champs end up adding Candice Dupree, Katie Lou Samuelson, Tamera Young and Mikiah Herbert Harrigan (none of whom look particularly stellar by the metrics at this stage of their careers). If the new-look Storm falter, A’ja Wilson and the Aces could be next in line with dominant center Liz Cambage returning to join a number of offseason pickups. The model also gives double-digit odds to the Connecticut Sun, who made sure to keep together their star trio of DeWanna Bonner, Alyssa Thomas and Brionna Jones this offseason. The Sun made the playoffs despite a sub-.500 record last season — and they were much better in 2019, the league’s most recent full season, coming within a game of the WNBA title.

Speaking of teams that could be looking to bounce back from an aberrant 2020, don’t be surprised if the Washington Mystics rise quickly in our Elo depending on how soon Elena Delle Donne comes back this season. Although her surgically repaired back might not be ready for the start of the schedule, Delle Donne was by far the league’s best player in 2019, when she led the Mystics to their first WNBA crown. In her absence, forward Myisha Hines-Allen put up potential star numbers last year, and she could be a good complement to Delle Donne, Clark, Natasha Cloud, Tina Charles and Ariel Atkins. And, of course, all eyes will be on the young talent accumulated by the Dallas Wings — who have both of the top two rookies picked in April’s draft (Charli Collier and Awak Kuier) — and the Liberty, who got only three games from 2020 No. 1 overall pick Sabrina Ionescu last season before an ankle injury ended her rookie campaign. With Ionescu healthy alongside a revamped supporting cast led by Howard and Whitcomb, New York should at least be a strong candidate to improve on last year’s dreadful 2-20 record.

Overall, after the game made clear strides last season in the face of great hardship, it will be exciting to see what the WNBA can do with more exposure and more stars in action for 2021. And thanks to our new interactive, you’ll be able to follow these and all the other storylines for the league, tracking your favorite team’s progress and monitoring the best matchups to watch all season long.

Check out our latest WNBA predictions.

Source: We Built A WNBA Prediction Model For The 2021 Season

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