107 lines
3.9 KiB
Markdown
107 lines
3.9 KiB
Markdown
# Outfield Arm Rating Scale - Quick Reference
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## Normal Distribution (-6 to +5)
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```
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NORMAL DISTRIBUTION CURVE
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Elite Very Weak
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-6 0 +5
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| -5 -4 -3 -2 -1 | 0 | +1 +2 +3 +4 +5 |
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|<--- Above Average --->|Average|<--- Below Average --->|
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| (Top 50%) | | (Bottom 50%) |
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0.6% 2.3% 6.7% 16% 31% 50% | 50% 31% 16% 6.7% 2.3% 0.6%
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Players at each percentile
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```
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## Rating Breakdown
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### Elite Arms (Negative Ratings = Better)
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| Rating | Description | Z-Score | Approx % | Frequency |
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|--------|-------------------|----------|------------|------------|
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| **-6** | Elite Cannon | > 2.5 | ~1% | Very Rare |
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| **-5** | Outstanding | 2.0-2.5 | ~2% | Rare |
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| **-4** | Excellent | 1.5-2.0 | ~3% | Uncommon |
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| **-3** | Very Good | 1.0-1.5 | ~5% | Above Avg |
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| **-2** | Above Average | 0.5-1.0 | ~15% | Common |
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| **-1** | Slightly Above | 0.0-0.5 | ~30% | Common |
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### Average Arms
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| Rating | Description | Z-Score | Approx % | Frequency |
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|--------|-------------------|----------|------------|------------|
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| **0** | Average | -0.5-0.0 | ~40% | Very Common|
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### Weak Arms (Positive Ratings = Worse)
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| Rating | Description | Z-Score | Approx % | Frequency |
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|--------|-------------------|----------|------------|------------|
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| **+1** | Slightly Below | -0.8--0.5| ~20% | Common |
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| **+2** | Below Average | -1.2--0.8| ~10% | Above Avg |
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| **+3** | Poor | -1.5--1.2| ~5% | Uncommon |
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| **+4** | Very Poor | -1.8--1.5| ~2% | Rare |
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| **+5** | Very Weak | < -1.8 | ~1% | Very Rare |
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**Note:** Thresholds calibrated to actual data after 300x assist_rate weight compressed z-score distribution.
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## Expected Distribution (162 Players)
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Based on normal distribution, in a typical season with ~162 qualified outfielders:
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| Rating Range | Count | Description |
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|-------------|-------|-------------|
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| -6 to -4 | ~10 | Elite/Excellent arms (top tier) |
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| -3 to -1 | ~62 | Above average to very good |
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| 0 | ~18 | Average (largest single group) |
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| +1 to +3 | ~62 | Below average to poor |
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| +4 to +5 | ~10 | Very poor/weak arms (bottom tier) |
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## Comparison to Previous Scale
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**Old Scale:** -6 to +2 (9 levels)
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- Skewed toward negative (better arms)
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- Limited granularity for weak arms (only 3 levels: 0, +1, +2)
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- Not symmetric
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**New Scale:** -6 to +5 (12 levels)
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- Symmetric distribution around 0 (average)
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- Equal granularity for elite and weak arms
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- Follows normal distribution percentiles
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- More meaningful differentiation at extremes
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## Practical Guidelines
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### For Elite Arms (-4 to -6)
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- Strong deterrent effect on baserunners
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- Frequently throw out runners attempting to advance
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- High home plate assist count
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- Can turn singles into outs on aggressive baserunning
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### For Average Arms (-1 to +1)
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- Typical MLB outfielder arm strength
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- Will get assists but not at elite rate
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- Runners will test them opportunistically
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- Positioning and reads matter more than raw strength
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### For Weak Arms (+3 to +5)
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- Runners take extra bases frequently
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- Low assist totals relative to opportunities
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- May be limited defensively to certain positions
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- Often DHs or older players playing outfield occasionally
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## Integration Notes
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When implementing, ensure:
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- Minimum 50 balls fielded for qualification
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- Position-specific baselines (LF/CF/RF different)
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- Z-score calculation accounts for position
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- Players below sample size get 0 (average) rating
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---
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**Reference:** `/docs/of_arm_rating_improvement_proposal.md` for full methodology
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