After the first month of the season, the NBA Rookie of the Year race was seemingly locked up. Ben Simmons, who missed all of last season due to a broken bone in his foot, put up ridiculous numbers from the jump as the 76ers’ starting point guard. In October he averaged 18.4 points per game, 9.1 rebounds, 7.7 assists, 1.4 steals, and 0.4 blocks. November was just as good: 18.6 points, 9.5 rebounds, 6.9 assists, 2.7 steals, and 1.0 blocks. When ESPN released their Defensive Real Plus-Minus marks for the season around that time, Simmons debuted at the top of the PG position. Even today he sits third with a +1.75 mark. The dude can do it all.
Simmons is a statistical monster, and it’s clear that, even with a little shooting regression, it would take a miracle for other rookies to even be competitive in the ROY race, let alone win. And yet, other candidates have gotten some recent buzz around the industry. Donovan Mitchell and Jayson Tatum have certainly had outstanding rookie seasons. They already look like starters at worst and potential stars at best.
Not every site currently offers odds on the ROY race, but according to William Hill, here are the odds as of Jan. 10:
Simmons: -450
Mitchell: +400
Tatum: +2000
That makes Simmons’ implied probability of winning of about 80 percent. Is that fair?
Historical ROY Voting Trends
To answer that question, let’s look at the past ROY winners and what they might have in common. Do voters typically take the best scorer? If so, Mitchell leads in that category and could be a value. Do voters weigh advanced stats like BPM (Box Plus-Minus), VORP (Value Over Replacement Player), or WS (Win Shares)? If so, Tatum could be a value. Let’s look.
The table below shows a variety of metrics and whether the winner of the ROY race in that season led the rookie crop in that specific statistic. The stat called “PRA” means points plus rebounds plus assists (the sum of those per-game marks). In the 2017-18 row is the current leader of that metric, while the “Total” row at the bottom of the table is how often that metric predicted the ROY winner.
The most predictive metric is the combination of points per game, rebounds per game, and assists per game, which Kevin Pelton of ESPN first noticed a couple years ago. That metric has successfully predicted the ROY in 14 of the past 17 seasons, including 13 straight years until, well, last season. That was a bit of anomaly, however: Joel Embiid easily led rookies in PRA, but of course he played just 31 games. The award instead went to Malcolm Brogdon, who was a surprising first-year starter and was considered the best year-long rookie by advanced stats. Interestingly, Dario Saric actually had a higher PRA than Brogdon, although he likely competed for votes with his teammate in Embiid. It was an outlier year, and if Embiid had played even a semi-normal workload, he would have been a massive favorite.
The 2017-18 Rookie Crop
Of note, advanced metrics have had fairly low predictive value in the ROY race. Only eight win-share leaders have won the award since 2000, which does not bode well for Tatum, who leads rookies in only that category. To simplify things: Voters do exactly that — keep it simple. They’re looking for the best combination of raw box score metrics. So how much does Simmons lead the other rookies in those? Umm, a lot.
Among the rookies this season who are averaging at least 10 minutes and 10 points per game, Simmons absolutely dominates the field in PRA. Mitchell is averaging the most points per game, but Simmons’ 8.4 rebounds per game and 7.5 assists per game are historically-good marks for anyone, let alone a rookie. In terms of raw statistical production, the field just can’t compete with Simmons. That is especially true with a guy like Tatum, who is getting buzz because of unsustainably hot shooting and role on a surprising Celtics team, but he statistically is nowhere close to Simmons. In fact, Kyle Kuzma, Lonzo Ball, Lauri Markkanen, and Dennis Smith all have superior PRA marks.
How Does Simmons Fit in ROY History?
Let me hammer this home. Here are all rookies since 2000 who have played at least 10 minutes per game and have averaged 10 points per game. Simmons not only leads this year’s crop of rookies in PRA — he’s statistically (measured solely in per-game value) the second-best rookie of the past 20 years, sitting behind only Blake Griffin in PRA.
Weird things happen, and Simmons might not win. However, based on historical voting trends and his performance thus far, he seems very likely to do so. If the betting market shifts in the favor of Mitchell or Tatum over the second half of the season, and Simmons still has a commanding lead over the field in PRA, there could be nice value in taking the stud 76er.
Photo via Bill Streicher-USA TODAY Sports
