Where FiveThirtyEight And ESPN’s 2022-23 NBA Forecasts Agree — And Disagree
‘Tis the season for NBA prognosticating, with the league returning to the court for 2022-23 on Tuesday night. We released our forecast, which is based on FiveThirtyEight’s RAPTOR player ratings and projections, last week – you can check out our interactive here. But we aren’t the only ones peering into the crystal (basket)ball: ESPN also released a forecast based its own rating system, the Basketball Power Index, which tracks team strength slightly differently than RAPTOR does.1 So we thought it would be fun to see how closely the systems match up and which teams look better or worse in each.
Overall, there is a lot of agreement between RAPTOR2 and BPI. (This might be unsurprising to anyone who saw our respective Boston Celtics predictions for the NBA Finals last summer.) The correlation coefficient between the two models’ preseason strength ratings is 0.91, indicating a very strong relationship — generally speaking, RAPTOR likes the same teams as BPI. However, there are some teams that each system likes (or dislikes) slightly more than the other:
Let’s start on the higher-for-RAPTOR side of things, and with a disclaimer: We categorically deny building in any bias toward the team called the Toronto Raptors when creating the metric called RAPTOR — it’s just pure coincidence that “Robust Algorithm (using) Player Tracking (and) On/Off Ratings” happens to spell out that team’s name as an acronym. 😉 But it’s interesting nonetheless to see Toronto rank 11 slots higher in preseason RAPTOR (No. 5) than BPI (No. 16). The Raptors are coming off a solid bounceback season from a disastrous 2020-21, and they have a wealth of players with positive projected ratings. But BPI is not at all sold on Toronto’s offense, ranking it just 23rd in the NBA (compared with RAPTOR, which ranks it No. 13).
Other teams RAPTOR likes better than BPI include the Miami Heat (No. 3 in RAPTOR versus No. 13 in BPI), Denver Nuggets (No. 2 versus No. 11) and Portland Trail Blazers (No. 18 versus No. 25). Of the three, the betting markets would probably side with RAPTOR on the Nuggets and Blazers and with BPI on the Heat, since Miami faces conflicting factors that makes its upside less clear-cut.
At the other end of the spectrum, BPI is notably higher than RAPTOR on the Atlanta Hawks and Milwaukee Bucks.
Both systems agree the Hawks have an elite offense — BPI ranks it No. 1 while RAPTOR ranks it No. 2 — but disagree about their defense. BPI has Atlanta ranked No. 9 on D, while RAPTOR pegs the Hawks’ defense at No. 17. Both would be upgrades over their No. 26 finish in defensive efficiency last season, but the contributions of newcomer Dejounte Murray (who carries a good defensive reputation but average RAPTOR ratings at that end) will go a long way toward determining which metric more accurately judges Atlanta’s potential.
For Milwaukee, the difference is more on the offensive side of the ball – although the two systems’ disagreement on the Bucks is fairly comprehensive. BPI has Milwaukee ranked No. 4 on offense and No. 12 on defense — in line with the team’s performance last season — while RAPTOR flips that around to a No. 19 ranking on offense and No. 4 ranking on defense.3 Some of that owes to the injury Khris Middleton is still recovering from (remember, these are all current ratings), which takes a bite out of Milwaukee’s projected rotation strength. But even though RAPTOR expects him to be available for most of the regular season, it still calls for the Bucks to win fewer than 50 games.
The market definitely thinks BPI is closer to the truth when it comes to Milwaukee, and I can’t disagree much. But that’s the beauty of looking at different systems, particularly when they arrive at their projections in different ways: You learn something new whenever you pop open the hood and start poking around. And you can keep track of how both systems view your favorite team all season long by checking out ESPN’s BPI playoff odds and team ratings, and our NBA predictions dashboard.
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