Carry-Over Lottery Allocation: Practical Incentive-Compatible Drafts
The 'Carry-Over Lottery Allocation' framework uses multi-year playoff outcomes to assign draft picks, removing the reward for losing.
A team of researchers including Timothy Highley, Tannah Duncan, and Ilia Volkov has published a paper proposing a fundamental redesign of the NBA draft lottery system. Their 'Carry-Over Lottery Allocation' (COLA) framework aims to solve the persistent problem of 'tanking,' where teams deliberately lose games to improve their odds of securing a top draft pick. The core innovation shifts the evaluation of team quality from a single season's win-loss record to a multi-year assessment of playoff outcomes. This paradigm change seeks to decouple short-term failure from long-term reward.
Under the proposed COLA system, every team that misses the playoffs receives the same number of lottery tickets, removing the direct incentive to be the absolute worst. However, the system introduces complexity to maintain fairness: lottery tickets accumulate and carry over into future drafts if not used, but a team's ticket bank is reduced by achieving playoff success or by actually winning a top selection. The researchers argue this preserves the excitement of a lottery while aligning team incentives with winning. The 35-page paper also addresses practical implementation hurdles, such as transitioning from the current system, handling traded draft picks, and managing exceptionally strong draft classes where teams might prefer a lottery chance over a playoff berth. For these 'super drafts,' they propose a truth-elicitation mechanism to identify the year and temporarily expand lottery eligibility to include more teams, preserving the system's incentive-compatible nature.
- Replaces single-season standings with multi-year playoff outcomes to determine draft eligibility, a fundamental shift in evaluating 'weak' teams.
- Awards equal lottery tickets to all non-playoff teams, directly removing the incentive to have the worst record ('tanking').
- Includes mechanisms for 'super drafts,' using a truth-elicitation process to identify years where teams might prefer the lottery over playoffs.
Why It Matters
This research applies game theory to solve a major real-world sports economics problem, potentially reshaping how leagues design competitive balance mechanisms.