# 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.

