COLA Draft Mechanism Overview

• COLA is a draft mechanism that uses a multi-season ticket system where non-playoff teams accrue lottery tickets to secure top draft choices.
• The mechanism adjusts team ticket counts via multiplicative reductions after playoff successes or lottery wins, ensuring dynamic fairness.
• Empirical simulations and a truth-elicitation process validate COLA’s incentive compatibility and its effectiveness in maintaining competitive parity.

The Carry-Over Lottery Allocation (COLA) Draft Mechanism is a practical, incentive-compatible system designed to allocate draft picks in professional sports leagues, with an initial focus on the NBA. COLA fundamentally reconfigures the traditional lottery draft process by implementing a multi-year, ticket-based accumulation and carry-over structure: non-playoff teams receive an equal accrual of lottery “tickets” each season, ticket counts persist until diminished by playoff success or winning a top lottery pick, and all major incentives to deliberately lose (tanking) are eliminated under standard league conditions. This mechanism maintains both competitive balance and fan engagement while rigorously addressing edge cases in league dynamics (Highley et al., 2 Feb 2026).

1. Mechanism Definition and Formal Structure

Let $N$ denote the number of teams. Each team $i$ possesses an integer “lottery index” $T_i(t)$ at the start of season $t$, representing the number of lottery tickets. The progression is as follows:

• Ticket Allocation: At season’s end, all non-playoff teams ($\ell_t = \{i : i \text{ not in playoffs in } t\}$) increase their index by a uniform $\alpha$ (with $\alpha = 1000$ in the reference scheme): $T_i(t^-) = T_i(t) + \alpha$. Playoff teams’ indices remain unchanged: $T_j(t^-) = T_j(t)$.
• Lottery and Carry-Over: The draft lottery allocates the top four picks. Teams not drawing a top-4 pick retain their entire index into the following year: $T_i(t+1) = T_i(t^-)$.
• Diminishment after Success: Winning a top-4 pick or playoff progression yields multiplicative reduction. For lottery winners, $i$0, $i$1 denoting draft slot; for playoff teams, $i$2, $i$3 denoting playoff round exited.
• Multipliers: $i$4, $i$5, $i$6, $i$7; $i$8, $i$9, $T_i(t)$0, $T_i(t)$1, $T_i(t)$2.
• Lottery Probabilities: The chance that non-playoff team $T_i(t)$3 draws the top pick in year $T_i(t)$4 is $T_i(t)$5; top-4 picks are drawn without replacement by these weights.

This dynamic system decouples draft incentives from recent-season record alone and rewards persistent underperformance while ensuring that only eligible teams (those not achieving playoff or draft success) maintain high ticket counts over multiple years (Highley et al., 2 Feb 2026).

2. Theoretical Properties and Incentive Compatibility

COLA is constructed to ensure robust anti-tanking properties under standard assumptions:

• Incentive-Compatibility: Each team’s dominant strategy is to maximize its playoff qualification prospects prior to elimination, as post-elimination performance does not affect ticket accrual. Once eliminated, all non-playoff teams receive the same increment, so late-season tanking yields no marginal benefit.
• Playoff vs. Non-Playoff Preference: For any year not designated a “strong class,” the utility from making the playoffs strictly dominates that from missing them: $T_i(t)$6, provided playoff rewards exceed any decrement in expected draft value due to ticket diminishment.
• Convergence and Steady-State: The Markov process defined by the ticket distributions under mild mixing assumptions has a unique stationary distribution $T_i(t)$7. Each team's lottery weight $T_i(t)$8 oscillates over time, ensuring that no franchise is permanently advantaged or disadvantaged—the process lacks absorbing states and prevents persistent tanking or dynastic dominance.

A plausible implication is that COLA achieves league-wide competitive balance in expectation over sufficiently long horizons, even as cyclical variations persist for individual teams (Highley et al., 2 Feb 2026).

3. Detailed Operational Considerations

Transition to COLA and associated logistics are addressed as follows:

• Historical Seeding: A historical anchor year establishes initial indices for each franchise by retrospective COLA application, forming a “balance sheet” of tickets at launch.
• Traded Picks: Picks traded without protection are excluded from the lottery and slotted at positions 5 or later. Only 1–4 protections are allowed, reverting top pick wins back to the original team (which then has its ticket index diminished appropriately); all other pick protections are forbidden to prevent manipulation of ticket accumulation.
• Draft Class Variation: Teams identifying negligible value in a specific draft cohort may “opt out” of a lottery win for a penalty of 2α tickets, maintaining monotonicity in expected utility. In strong classes (addressed below), eligibility is dynamically broadened (Highley et al., 2 Feb 2026).

This ensemble of rules preserves incentive-compatibility while adapting to league realities, ensuring practicality and ease of integration with existing practices.

4. Exceptionally Strong Draft Classes: Truth-Elicitation and Adaptive Eligibility

During years in which draft class strength is so high that playoff participation may be less preferred than lottery eligibility for some teams, the core anti-tanking assumption is violated. COLA addresses this challenge via a truth-elicitation mechanism based on expert forecast aggregation:

• Survey Procedure: A panel of sports-media experts provides forecasts before the season, choosing among six options corresponding to progressively broader expansion of lottery eligibility (up to including the league champion). Each expert also predicts the distribution of others’ responses.
• Line-Setting Algorithm: The mechanism identifies the minimal round $T_i(t)$9 for which the cumulative fraction of experts recommending lottery expansion to that round or deeper exceeds 50%. All teams eliminated in round $t$0 participate in the lottery; if fewer than eight teams remain excluded, the lottery becomes nearly universal with no tickets awarded.
• Incentive-Compatibility via RBTS: The Robust Bayesian Truth Serum (RBTS) is employed for aggregation, with quadratic scoring for peer predictions and partial peer-comparison for information scores. This assures truthful reporting as a strict equilibrium in the elicitation process, preserving the foundational incentive structure even in anomalously strong draft years (Highley et al., 2 Feb 2026).

This adaptive procedure operationalizes a dynamic, expert-driven “line” for playoff-lottery eligibility, directly countering perverse incentives arising in exceptional draft classes.

5. Simulation-Based Performance and Empirical Behavior

Performance validation through stylized Monte Carlo simulation over 1,000 seasons, with standard league parameters, reveals the following behaviors:

• Equity: The mean draft pick position for all teams over the simulation horizon is approximately 15, indicating a lack of persistent underprivileged or privileged franchises.
• Dynamism: No team missed the playoffs more than about 10 consecutive times in 50 runs of 100 seasons each. Team ticket trajectories display oscillatory patterns, consistent with the absence of absorbing extremes in the Markov process underpinning COLA.
• Negligible Edge Tanking: In rare cases where, for example, a team might attempt to swap a high-index opponent into the lottery via an additional loss, the change in expected draft pick win probability is less than 1.5% in 90% of simulated seasons.
• Robustness: These results confirm COLA’s long-run balance, transparency, and its capacity to neutralize tanking incentives under realistic operational scenarios (Highley et al., 2 Feb 2026).

6. Context, Significance, and Future Directions

COLA represents a substantial paradigm shift in the allocation of draft capital by integrating multi-seasonal performance, explicit long-term incentive alignment, and structural deterrence of tanking. By retaining the lottery format, it preserves critical aspects of league transparency and fan engagement, while its truth-elicitation component and adaptive rules for strong draft classes further reinforce anti-gaming guarantees.

The mechanism’s reliance on explicit, verifiable empirical simulations as well as formal incentive-compatibility proofs situates it as an analytically robust alternative to contemporary draft systems. Potential extensions may arise in investigating further refinements to the truth-elicitation process, impact assessment in leagues with non-NBA playoff structures, and empirical tracking upon real-world adoption (Highley et al., 2 Feb 2026).