How much would the NBA Draft Lottery really change? (and other thoughts)

by Aaron Barzilai and Mike Lopez

The NBA’s competition committee has recommended some changes to the NBA Draft Lottery starting with the 2019 Draft as reported by Woj. Thanks to the reporting of Jeff Zillgit and others we have a sense of the new lottery rules. Will they make a real difference? In a word, yes. But also, no.

We’ve estimated the lottery odds based on the public reporting of the proposal. Details of our assumptions appear below. While they probably don’t match the NBA proposal exactly, they illustrate the kind of change it is likely to have. Given the assumptions, the chart below shows the expected pick for each team based on their rank in the lottery.

As you can see, the change does have a pretty big impact at the top of the draft in terms of the pick the teams should expect. The team with the worst record will pick about one spot lower on average in the proposed system (expected pick 3.7) than under the current one (expected pick 2.6). The impact on the team with the 2nd worst record is similar but slightly less.

This reduces the chance that a Process-style approach of racing to the bottom for a period of time will produce multiple All-NBA players (note: we prefer to use the term All-NBA as it is slightly clearer than the amorphous “superstar” term). As a result, it should reduce the incentive to “tank” somewhat.

At the same time, it’s also clear that you’ve increased the incentive to tank among the mid-to-late-lottery teams. For example, the benefit of dropping from 14th to 13th or from 11th to 10th is bigger under the new proposal than the current lottery.

When you think about the specifics, which teams this year would be behaving differently if the 2018 NBA lottery followed the new proposal instead of the current rules? Teams that are already bad can still expect a better pick by dropping down in the standings.

• Would New York (6th lowest over/under per Westgate) be less likely to trade Carmelo Anthony and look to the future with Kristaps Porzingis?
• Would Chicago (lowest over/under per Westgate) be less likely to buy out Dwayne Wade?

If you think that the cost in terms of fan support, culture, and other intangibles isn’t much different dropping from 11th to 9th as it is going from 5th to 3rd, don’t expect too much change among the teams that already are expected to play poorly.

What appears to be reduced is the incentive to make a big drop to the very bottom of the standings. Average teams that are competing for low playoff seeds are now looking at a longer journey if they blow it up. How often does that really happen though? Do teams like this year’s Clippers (expected to be the 7th seed in the playoffs), Blazers (8th), or Hornets (tied for 7th in East) that have multiple players that rank among the top 30 to 50 in the league often choose to tank?

It’s hard to think of a team that was over 0.500 and in the playoffs when the front-office intentionally chose to tank for a chance at the #1 pick instead of having their hand forced by injury, trade demands, or other unforeseen circumstance. If anything, these sorts of teams have historically looked at their team with rose-colored glasses and thought they were really competing for home-court advantage, so they haven’t tanked in the offseason. Then, if they turn out to underperform once the season is underway, they recognize they are a mid-to-late lottery team and behave accordingly. By then, though, we think of them the way we do of the Mavericks or Magic today.

More details about our assumptions appear below. To keep this post from being even longer than it is, look for some random thoughts on the draft and league from Aaron in a separate post.

The Gory Details

Jeff Zillgit and others have reported the main changes for lottery as

The three highest lottery seeds would each be allocated 14% odds to win the lottery, compared to the 25%, 19.9% and 15.6% for those three teams in the current lottery system, which has been in place since 2005. The odds for the remaining lottery would decrease smoothly, with approximately a 1%-2% difference between lottery teams.

The number of picks determined by the lottery will increase to four, compared to three in the current system.

As a result, we are guessing that the odds for the first pick and therefore number of the 1,000 lottery balls allocated to each team are:

We simulated the lottery 1,000,000 times to determine the chances that a team with a given rank would finish with each pick. Here are the results:

Some summary stats include:

For reference, here are similar charts for the current lottery system: