The Alliance Rating System
How the Alliance Rating System Works
- The Alliance Rating System represents your team’s current rating, similar to RPI in college softball.
- Teams exchange rating points based on the outcome of games.
- A team that performs better than expected gains rating points.
- A team that performs worse than expected loses rating points.
- Teams are incentivized to play stronger opponents.
- Stronger teams must consistently beat weaker teams to maintain or improve their rating.
- Weaker teams can improve their rating by playing stronger teams, even without winning many games.
League Division Defaults
- Super Division teams and 10U teams start with a default rating of 1600.
- Champions Division teams start with a default rating of 1400.
Alliance Rating Carryover Rules
If your team renews its membership (keeping the same Team ID), your previous season’s rating carries over under these conditions:
- Same Age & League Division: Retain 75% of your previous rating.
- Same League Division, Different Age: Retain 25% of your previous rating.
- If a team’s final rating was below the League Division Default, it resets to the default for the next season:
- Example: If a Super Division team ended with a 1580 rating in 2024, it starts at 1600 in 2025.
- If a team changes League Divisions, the rating resets to that division’s default:
- Super Division → 1600
- Champions Division → 1400
Why Renewing Your Team Matters
- Retaining the same Team ID ensures historical data continuity.
- Carryover rules provide teams with more accurate starting ratings instead of resetting every season.
- Helps new teams rise faster in the rankings.
- If a new team beats a high-rated team, they gain more points earlier.
- If a new team loses to a high-rated team, they don’t lose as many points.
What is the Alliance Rating System Used For?
Your Alliance Rating determines your team’s placement in:
- League & National leaderboards
- League rankings appear on each Alliance Member League website and your Team Profile.
- National rankings appear on the Alliance National Leaderboards.
- League Championship Seeding
- AFCS Seeding Committee Evaluations
- (Note: Elo rating is only one factor in the seeding process. Click here to review the full process.)
Elo Formula
The Alliance Rating System follows the Elo formula:
$$ \text{New Rating} = \text{Current Rating} + K \times (\text{Actual Score} - \text{Expected Score}) $$
Where:
- Current Rating is a team's Elo rating before the game.
- K-factor determines the maximum adjustment per game:
- Bracket games: \( K = 32 \)
- All other games (pool play, showcase, etc.): \( K = 16 \)
- Actual Score (\( S \)):
- \( S = 1 \) if the team wins.
- \( S = 0.5 \) for a tie.
- \( S = 0 \) if the team loses.
- Expected Score (\( E \)) is calculated based on the opponent's rating:
$$ E = \frac{1}{1 + 10^{\left(\frac{\text{Opponent Rating} - \text{Team Rating}}{400}\right)}} $$
- If a team wins: it gains more points if it defeats a higher-rated opponent and fewer points if it defeats a lower-rated opponent.
- If a team loses: it loses more points if it was expected to win and fewer points if it was expected to lose.
- If a weaker team upsets a stronger team: the rating adjustment is larger.
Elo Rating Calculation Example
In this example, we assume:
- Team A is a strong team with an average Elo rating of 1800.
- Team B is a weaker team with an average Elo rating of 1500.
- The game type is a pool game, meaning the K-factor is 16.
Step 1: Expected Score Calculation
The expected score formula is:
$$ E_A = \frac{1}{1 + 10^{\left(\frac{R_B - R_A}{400}\right)}} $$
Substituting the values:
$$ E_A = \frac{1}{1 + 10^{\left(\frac{1500 - 1800}{400}\right)}} $$
$$ E_A = \frac{1}{1 + 10^{-0.75}} = \frac{1}{1 + 0.1778} = \frac{1}{1.1778} \approx 0.849 $$
For Team B:
$$ E_B = 1 - E_A = 1 - 0.849 = 0.151 $$
Step 2: Elo Rating Adjustment
The new rating is calculated using:
$$ \text{New Rating} = \text{Current Rating} + K \times (\text{Actual Score} - \text{Expected Score}) $$
Scenario 1: Team A Wins
If Team A wins (\( S_A = 1 \), \( S_B = 0 \)):
$$ \Delta R_A = 16 \times (1 - 0.849) = 16 \times 0.151 = 2.42 $$
$$ \Delta R_B = 16 \times (0 - 0.151) = 16 \times (-0.151) = -2.42 $$
Result: Team A gains +2.4 points, and Team B loses -2.4 points.
Scenario 2: Team B Wins
If Team B wins (\( S_A = 0 \), \( S_B = 1 \)):
$$ \Delta R_A = 16 \times (0 - 0.849) = 16 \times (-0.849) = -13.58 $$
$$ \Delta R_B = 16 \times (1 - 0.151) = 16 \times 0.849 = 13.58 $$
Result: Team B gains +13.6 points, and Team A loses -13.6 points.
Final Thoughts
Because Team A is expected to win, the Elo adjustment is small when they do win. However, if Team B pulls off an upset, the Elo adjustment is much larger to reflect the unexpected outcome.
Why Elo?
- Most commonly used sports rating system
- Used by FIFA
- Used by Sagarin
- NFL/MLB/NBA/NHL
- College sports
- Used by 538.com
- NFL/MLB/NBA/NHL
Earning Points
- OFFICIAL SCORING: You must stream & score the game in AthletesGoLive (AGL) in order to receive points.
- EVENT: Use the AGL EVENT ID to identify the tournament you are playing in.
- OPPONENT: Ensure you select the correct opponent AGL ID when scheduling your games within AGL. This will help with the accuracy of the points awarded based on the matchup.
- If using team name you need to confirm the AGL ID next to the team name is correct to ensure we are accurately capturing your points based on your opponent.
- Reference the ALLIANCE TEAM LIST or your LEAGUE TEAM LIST to easily find your opponent's AGL ID.
- Enter the opponent's ALLIANCE ID if they do not have an AGL ID.
- TIE BREAKER (for teams facing off with the same rating):
Strength of Schedule > Strength of Victory > Runs Against > Runs Scored - The amount of points awarded for each game is based on the win probability of the game. If you are expected to win (i.e. your team has a higher rating than your opponent) you will receive less points for a win. If you are expected to lose, but end up winning, you will receive more points for a win.
Alliance Power Points
- Alliance Power Points (APP) will be awarded when traveling to a different League’s territory or when playing a traveling team from a different League in an Alliance endorsed event.
- Alliance Power Points will be awarded based on the following:
| 3 | Travelling Team Tie | 2 | Neutral Ground Tie | 2 |
|---|---|---|---|
| Traveling Team Loss | 1 | Neutral Ground Loss | 1 |
| Local Team Wins | 2 | ||
| Local Team Tie | 1 |
Questions?
Please contact info@thealliancefastpitch.com with any questions about Alliance Rating System.