BPI: Which teams open with best odds to win the title or reach the playoffs?

After winning the 2022 WNBA title, the Las Vegas Aces got stronger in the offseason by adding Candace Parker. The two-time MVP and two-time WNBA champion joined a roster already featuring a dominant starting five around 2022 MVP A’ja Wilson.

On the other side of the country, the New York Liberty also had a huge offseason, bringing in two former WNBA MVPs in Breanna Stewart and Jonquel Jones. Free agent point guard Courtney Vandersloot also signed with the Liberty to play alongside Sabrina Ionescu, the No. 1 draft pick in 2020.

According to Caesar’s Sports Book, the Aces and Liberty are tied for the best odds to win the 2023 championship at +120 each. Before the season tips, how might one attempt to evaluate the strength and potential for each of these teams, as well as the rest of the league?

Glad you asked.

The Basketball Power Index (BPI), developed by ESPN Analytics, is a method for quantifying a team’s potential based upon several factors, particularly the historical and projected contributions of the players that make up a team. BPI is part of a family of WNBA Metrics available for this season that also includes projected win/loss record, probability for each team of making the playoffs, projections for how far each team advances in the postseason (for example, the WNBA semifinals or WNBA Finals) and its chances of winning the championship, as well as predictions for every individual game this season.

Each of these metrics will iterate and update as the season progresses and new information becomes available. Injuries, trades and team performance once the games begin will be used as feedback. BPI is reported as a total value and can be broken down to offensive BPI (OBPI) and defensive BPI (DBPI). Once the season begins we will also report how much each BPI score has changed over a two-week span, both by rank and by score value itself.

Entering the season, the Liberty have the highest BPI in the league at 6.1 (3.5 OBPI, 2.6 DBPI). The Aces are second at 5.2 (3.7 OBPI, 1.4 DBPI), followed by the Connecticut Sun at 3.7 (1.7 OBPI, 2.0 DPBI), the Washington Mystics at 2.4 (-0.4 OBPI, 2.8 DPBI) and the Atlanta Dream at 0.2 (-0.6 OBPI, 0.9 DPBI).

A look at the BPI:

What does that tell us?

BPI estimates that the Aces will have the best offense in the league, which makes sense because Las Vegas led the WNBA in offensive rating by a significant margin last season, averaging 111.9 points per 100 possessions. Per BPI, the new-look Liberty are projected for a huge improvement on offense, ranking No. 2 behind the Aces in OBPI. But behind addition of dominant bigs Jones and Stewart, the Liberty are projected to have the second-best defense in the league as well, trailing only Elena Delle Donne and the Mystics at that end of the court. The Sun, despite losing Jones, still project to be a balanced team on both sides of the ball and boast the third-best BPI score in the league.

So which team is the favorite to win the 2023 title?

In the BPI’s projected win/loss and playoffs probability estimators, the Aces are ahead of the Liberty and on top of the WNBA. The Aces project to 27.6 wins vs. the Liberty’s 27.1 wins, and while both teams have 99.9% probability of making the playoffs, the Aces project to slightly better odds than the Liberty to reach the WNBA semifinals (82.1% vs. 80.4%) and WNBA Finals (57.5% vs. 55.5%) and to win the championship (35.6% vs. 33.5%).

How can the Liberty have the highest BPI score but fall behind the Aces in the projected season results?

Look again at the BPI’s top five teams. The Aces are the only Western Conference team, while the Liberty are joined in the top five by the Sun, Mystics and Dream. Even though the WNBA no longer uses traditional Eastern/Western conference playoffs and divisional seeding, the WNBA schedule skews toward a higher concentration of more local games. What are considered Eastern Conference teams play more games against the East, and Western Conference teams play more games against the West.

As the WNBA schedule increases to 40 games this season, the Liberty will play a higher concentration of games against opponents ranked more highly by BPI than will the Aces. According to the models, this makes the Aces more likely to end up with the slightly better record even if the Liberty might project as the slightly better team. And a better regular-season record means a higher seed in the playoffs, and thus homecourt advantage. In a situation where the differences in expected quality between teams was already very thin, homecourt advantage could help to potentially put one team over the top.