The Michi-chan DMVDerby Power Rankings

Updated: June 20, 2026

Objective

To create a rankings system that in an environment where there are multiple leagues (entities) and where there is not a level schedule of games (e.g. one league may play 3 eligible games per year while another league plays 6).  The system must afford similar opportunities for rankings to leagues that have fewer game opportunities while acknowledging their achievements in those games.  The system must also address the unique structures of teams within each league.

The decision to center the rankings on leagues as opposed to teams are also intended to acknowledge the training, coaching, athleticism and overall culture at the league level.  Not only all of that, but it is also a wonderful opportunity for bragging rights. 

Eligible Leagues

Each league would be considered an “entity”.  Any team roster from that league would be considered representing that entity.  Therefore, the team’s level (A, B, etc.) would not be taken into consideration.   Only leagues that are based in the District of Columbia, Maryland, Virginia and Delaware are eligible to be a DMVDerby entity.  Statewide, borderless and collective teams cannot be eligible entities.   As of June 19, 2026, the following DMVDerby leagues/entities are eligible for ranking.  These are also the names recognized in the event of a tie in rankings (second tiebreaker): 

• 301 Derby Dames ("301" will sort first)
• Charlottesville Roller Derby
• DC Roller Derby
• Diamond State Roller Derby
• Dominion Derby Girls
• Frederick Roller Derby
• Fredericksburg Roller Derby
• Free State Roller Derby
• Ghost Fleet Roller Derby
• Iron Mountain Roller Derby
• NOVA Roller Derby
• Patuxent Roller Derby
• River City Roller Derby
• Rocktown Rollers
• Southern Delaware Roller Derby
• Twin Valleys Roller Derby
• Virginia Men's Roller Derby

If at a later time, the Power Rankings are extended to the Michi-chan Arizona District, those entities will be separately ranked and will compete only with other Arizona entities.

Eligible Games

 Only games that are played between two eligible entities will be considered.  The following games are not eligible: 

1. “Home team” games played between two teams from the same entity (for example Patuxent Kraken Skulls vs. Salty Beaches);
2. Any games that include at least one multi-league mash-up team, even if all of the leagues represented are eligible entities (e.g. “the world”);
3. Any game that ends with a tie score;
4. Any otherwise eligible game where the total number of points scored between both teams is less than 150; and
5. Any game where there are scoring deviations from the standardized rule set (e.g. “shenanigans” games). 

Games that are stopped before the end of the second period will be considered complete games as long as there have been at least 150 points accumulated between both teams.

Unlike the former Arizona Power Rankings, the 2026 era Michi-chan Power Rankings are compatible with different rulesets such as WFTDA, USARS, MRDA and RDCL without specific adjustments for each ruleset. Entities on banked track will be combined in the rankings and will compete with flat track entities. Likewise, entities that do both banked and flat track will have all of their games combined into the single entity. 

We have no plans to rank juniors with adults.  If there is a massive growth of juniors in the region, we may consider a separate Power Rankings for juniors, but we are nowhere near that point.

All adult entities will compete with each other without regard to gender. 

Eligibility Period

Games that are considered eligible towards an entity’s total power score are limited to those played within the past 365 days (1 year rolling calendar).  Once 365 days have passed since the game was played, the game will age-off and the entity power score will be recalculated and the entity will be reranked.

Rankings Updates

The Power Rankings will be a daily systematic live ranking with the updates performed at around 3:10AM Arizona Time (AZT) (6:10AM Eastern during daylight time, 5:10AM during standard time).  Rankings will be based on all scores of qualified games already in the database as of when the daily run is made.  Any delays on getting a final score to Michi-chan Sports and it being entered into the database will skew the results until the data is entered. The Power Rankings source code and formulas do not involve any kind of AI.  During this run, all games scheduled in the future will be updated with the rankings of the leagues involved.  The final ranking to determine the parameters used for that game will be those that were ran at 3:10AM AZT on the day of the game.

On game days after a final score is declared in a Power Rankings eligible game, Michi-chan Sports may do a rankings update that will reflect on the website however, the ranking that was obtained in the 3AM systematic run will still apply for any additional game played the same calendar day for the purposes of the underdog adjustment (see below).

Raw Margin Score

The raw margin score is calculated by first adding up the total number of points scored by both teams of the game, dividing the number of points scored by the winning team into the number of total points scored and then multiplying that number by 100.

For example: The final score of the game was 161~85.  A total of 246 points were accumulated.  Divide 161 by 246 to reach 0.65447.  Multiply by 100 to reach the margin score of 65.447.  In other words, 65.447% of all game points can be attributed to the winning team. 

((WinScore / (WinScore+LossScore)) * 100)

"Underdog" Adjustment

In order to recognize games that are won by lower ranked entities, we will add an additional “bonus” to the Raw Margin Score.  The bonus will only be applied if the lower ranked team (higher ranking number) wins the game.  The ranking differential will be based on the whole number difference in rank between the two entities divided by the number of entities qualified to be ranked on game day.

((RankOfTheHigherRankedEntity – RankOfTheLowerRankedEntity) / TotalRankedEntities)

Underdog adjustment is only in effect if there at least 7 ranked entities.  Only games played after June 19, 2026 will be considered when tracking past performance for the underdog adjustment.

The adjustment will be based on the value of the equation above:

• If less than 0.200, there is no adjustment.
• If greater than or equal to 0.200 and less than 0.400, an adjustment of 5% will be given.
• If greater than or equal to 0.400 and less than 0.600, an adjustment of 10% will be given.
• If greater than or equal to 0.600 and less than 0.800, an adjustment of 15% will be given.
• If greater than or equal to 0.800, an adjustment of 20% will be given.

In cases where the lower ranked entity wins, the Underdog Adjustment will reward the winning team and penalize the losing team.

The underdog adjustment is only applicable in games where both entities are considered DMVDerby leagues and both entities already have a ranking.

If a league entity is playing multiple games in the same calendar day (AZT), the ranking for the league used to determine the underdog adjustment will remain the same for all games played that calendar day even if an earlier final score the same day results in a change of the instant ranking.

As an example, let’s say there are currently 15 entities eligible for ranking, the raw margin score is 65.447 (from the example above) and the lower ranked team (higher ranking number) wins:

RawMarginScore + (RawMarginScore * Adjustment) = GameMarginScore

Entity Power Score

The entity power score is determined by determining the sum of the margin scores of all eligible games won (PSW) and then the sum of the margin scores of all eligible games lost (PSL). Both values include any underdog bonuses that were applied.  The PSL is subtracted from the PSW and then divided by the number of games played in order to reach the entity power score.   The entity power score will be rounded to the nearest thousandth (3 digits to the right of the decimal point). 

For example, an entity has played four games, they won three games and lost one, the sum of the margin scores of the games won was 165.38 and in the game that was lost, the margin score was 51.62.  By subtracting 51.62 from 165.38, you would get a value of 113.76.  That value is then divided by the total games played (4) and results in an entity power score of 28.440.  The entity ranking will be based on that entity power score.

((SumOfWinningMarginScores – SumOfLosingMarginScores) / GamesPlayed)

In games where a DMVDerby entity plays against a non-DMVDerby entity, only the DMVDerby entity will have the margin scores considered for either a win or a loss. The league outside of the DMVDerby District will not be tracked and thus not eligible for a ranking.

Ranking

Rankings are based on the descending order of the power score for each eligible entity with at least 3 qualifying games played in a 365-day rolling calendar period.  In the event of a tie in power scores at the thousandth level, the first tiebreaker will be number of wins, the second tiebreaker will be the total number of points scored by an entity in all eligible games and the third tiebreaker will be the league name in alphabetical order.

In order to receive a ranking, an entity must play at least 3 qualifying games in a 365-day rolling calendar period.  Entities that currently do not have 3 qualifying games in a 365-day rolling calendar period will not receive a ranking even though their games will still be tracked and they will receive a ranking once they have achieved 3 games within the 365-day period.

Historic Snapshot

While live rankings are published on a daily basis, only those rankings that were executed on Tuesdays and Fridays will be a part of the permanent historical record.  The Tuesday rankings will be used for any display that shows whether an entity has gone up or down in rankings over the week.