Ping Pong Rating Systems Explained: Win Percentage vs Elo vs Strength of Schedule

By the Breakroom Battles team. The short version: rank players by who they beat, not how often they win, or your board will lie to everyone.

Every league needs to answer one question: who is actually the best? The system you pick decides whether your leaderboard earns trust or arguments. Here are the three families of rating systems, what each gets right, and where each one breaks.

Win percentage: simple, and wrong within a month

Sort players by wins divided by games. It takes one spreadsheet column, everyone understands it, and it fails the same way in every league: it rewards choosing weak opponents. The new hire farmer goes 9-1 against beginners and sits above your best player, who is 12-6 against killers. Both players can read the board and both know it is wrong. Win percentage also cannot handle uneven schedules, which describes every casual league ever: some people play 40 matches, some play 6.

Elo: the chess answer

Elo, the system chess made famous, fixes the core problem. Every player carries a number; when you win, you take points from your opponent, and the amount depends on the gap between you. Beat someone far above you and you gain a lot. Beat someone far below you and you gain almost nothing. Over time ratings converge toward true skill, which is why versions of Elo run everything from chess to competitive video games.

Elo's weaknesses in a small league are practical. It is path-dependent: the order of results changes the outcome, so early ratings swing wildly. New players start at a provisional number that takes many games to settle. And it never revisits the past: if the person you beat in week one turns out to be a shark, Elo gives you no credit retroactively.

Strength of schedule: the college sports answer

The third family solves the whole season at once instead of updating game by game. Given every result, it asks: what set of ratings best explains all of these outcomes together, weighing each win by the strength of the opponent? College sports rankings work this way. The elegant part is that it is retroactive by nature: when the player you beat keeps winning, your own rating rises, because your win got more impressive. Order of games does not matter, and uneven schedules are handled by construction.

What we use: an improved rating, on a 0 to 1 scale

Breakroom Battles uses the strength-of-schedule approach, recomputed across the whole board after every confirmed match. We call it the Power Ranking, and it reads as a decimal: everyone starts at 0.5000, strong players drift toward 1, and a rating only moves when a confirmed result justifies it. Two properties matter in practice:

• It cannot be farmed. Padding wins against beginners barely moves you. Beating your office champion moves mountains. The board rewards courage, not scheduling.
• Rank and rating stay distinct. Your rank is your position on the board (#3). Your Power Ranking is the decimal (0.6231) that produced it. When both are whole numbers, people confuse them; the decimal makes the difference visible at a glance.

Side by side

Want the bigger picture? Read how to start an office league that actually lasts, or see the league spreadsheet template if you are set on running the math yourself.