PickleBALLER/docs/rating-comparison.md

1.9 KiB

Rating System Comparison: Glicko-2 vs Pure ELO

Overview

This analysis replays all historical matches through the new ELO system to compare ratings.

Key differences:

  • Old system: Glicko-2 with separate singles/doubles ratings, RD, volatility
  • New system: Pure ELO with unified rating, per-point scoring, effective opponent formula

Summary

  • Total Players: 6
  • Total Matches Replayed: 29
  • K-Factor: 32
  • Analysis Date: 2026-02-26 11:55:18

Ratings Comparison (Sorted by New ELO)

Rank Player Glicko-2 Avg New ELO Diff Matches
1 Andrew Stricklin 1651 1538 -113 19
2 David Pabst 1562 1522 -40 11
3 Jacklyn Wyszynski 1557 1514 -43 9
4 Eliana Crew 1485 1497 +11 13
5 Krzysztof Radziszeski 1473 1476 +3 25
6 Dane Sabo 1290 1449 +159 25

Key Insights

Biggest Winners (rating increased)

  • Dane Sabo: +159 points (Glicko avg 1290 → ELO 1449)
  • Eliana Crew: +11 points (Glicko avg 1485 → ELO 1497)
  • **Krzysztof Radziszeski **: +3 points (Glicko avg 1473 → ELO 1476)

Biggest Losers (rating decreased)

  • Andrew Stricklin: -113 points (Glicko avg 1651 → ELO 1538)
  • Jacklyn Wyszynski: -43 points (Glicko avg 1557 → ELO 1514)
  • David Pabst: -40 points (Glicko avg 1562 → ELO 1522)

Why Ratings Changed

The new system differs in several ways:

  1. Per-point scoring: Instead of just win/loss, we use points_won / total_points. Winning 11-9 gives less credit than winning 11-2.

  2. Effective opponent formula: In doubles, your effective opponent is calculated as Opp1 + Opp2 - Teammate. This means:

    • Strong teammate → lower effective opponent → less credit for winning
    • Weak teammate → higher effective opponent → more credit for winning
  3. Unified rating: Singles and doubles contribute to one rating instead of two.