The lottery balls bounce your team’s way, and they jump to the 4th overall pick despite having had the 6th worst record. How much better off should you expect them to be because of their good luck? How much worse off would they be if they had dropped to the 8th pick? How much better is the first overall pick than the second?
While there is a lot of luck to drafting — and drafting has become more of a crapshoot over the last two decades — in the aggregate, the obvious is true: Having a higher draft pick is usually better. This is particularly true early in the draft, while the difference between one pick and the next is pretty negligible by the end of the first round.
As a fan of a team that had recently been (completely correctly) accused of tanking, I got to thinking about how valuable each draft pick is and to what extent the prospect of moving up one draft spot is worth the embarrassing displays of basketball incompetence that increase your team’s odds for a top pick. So I figured I’d develop an heuristic to estimate how valuable each draft pick is over the duration of that pick’s NBA career.
The historical value of draft picks
To measure the value of each draft pick, we need an objective metric to determine how much on-court value players provide to their teams. While there are a lot of options for all-in-one metrics, I’ll use Win Shares, as it gives us an intuitive and fairly reliable estimate of a player’s total career contributions on both offence and defense.
One Win Share is supposed to equal roughly one additional win that a team gets thanks to a player’s contributions, so this gives us a rough idea of how much better off a team will be overall thanks to their draft pick.
Using win shares, we can find the average value of each draft pick from 1979 (the year the three point line was adopted) to 2018 (so we have several years of data for every draft we include). There is a lot of noise; a couple of hall of famers or a few busts picked at a particular position affects the average value of that pick significantly. Third overall picks have somewhat famously outperformed second overall picks, but no one is upset if their team lands the second pick instead of the third one.
Thankfully, a logarithmic curve fits the first round data really well (R2 = .85), giving us a natural way to capture the value of each draft pick that smooths over this noise.
This curve (y = -17.3ln(x) + 71.5) gives us estimated values for each draft pick in the first round. These tell us roughly how valuable each draft pick is over the career of the player drafted by that pick. For instance, the average first overall pick produces just under 80 win shares over his career, whereas the average fifth overall pick produces about 48 win shares over his career.
“Why look at a whole career and not just the first X years?” you might object, with memories of young superstars switching teams buzzing in your head. My reasoning is simple: NBA teams nowadays very rarely lose great players for nothing, and we should assume that teams, on average, get fair value for trades, so whatever they get in exchange for a player who leaves should be roughly equivalent to the remaining value of that player. Plus, doing this keeps me from having to make arbitrary cutoffs for where to stop counting a draftee’s win shares and makes my life much easier without affecting the estimated gap between each draft pick’s value in any significant way.
How good is tanking?
The gap between each pick is biggest earlier in the draft; getting the first overall pick really is worth getting excited about, and the average gap between a top three pick and the fourth is roughly 20 regular season wins over a player’s career! The differences between the values of draft pick drops off later in the draft, to the point that the gap between the first and second picks is about the same as the gap between the fifteenth and thirtieth picks.
There’s an obvious caveat to all of this: each draft has different players and a different dynamic. Pretty much everyone involved in the NBA thinks that Victor Wembanyama, the ~7’5″ French kid projected to be this year’s first overall pick, is significantly better than your average first overall pick. Some drafts have a half dozen or so players who are all projected to be roughly equally good with no clear standout. The landscape of any individual draft will vary. In other drafts, the first and second picks might be equally valuable, while in others there may be huge gaps between the first few picks, though the results can be pretty different from the projections.
These are obviously very rough estimates, and there will be huge differences between these projections and the actual results for every draft. But I hope this heuristic helps put in perspective how valuable each draft slot is and how happy (or sad) you should be when the draft lottery shifts where your favorite team will be drafting.