From the NBA to eSports — using Classical Test Theory and Monte Carlo simulation to quantify how much of winning is skill, and how much is just chance.
When a team wins a championship, how much of that victory was earned through superior skill — and how much was simply the roll of the dice?
14 sports across traditional leagues, motorsport, and eSports — each positioned by their luck contribution. Hover to explore.
We decompose every observed outcome into its constituent parts — the skill that teams bring and the luck that fate deals. Extended to eSports with Monte Carlo simulation.
Calculate the variance of actual point distributions across all teams in each league season.
Run 100 simulations per season where every game is a coin flip — no skill differences exist.
The ratio of simulated (luck) variance to observed variance reveals luck's contribution.
Aggregate results over 9–23 seasons per sport to get robust, reliable estimates.
When skill matters, real seasons show clear hierarchies. In a luck-only world, points cluster near the average.
Explore the statistical fingerprint of every league analyzed.
Luck contributions fluctuate year to year. Click a league in the legend to toggle visibility.
Intuitively, more games should let skill shine through. The data largely supports this — with some notable exceptions.
Basketball rewards extreme height, shrinking the talent pool. With fewer viable candidates, the skill gap between teams narrows — making the NBA the most skill-driven league.
The NBA plays 82 games per season while the NFL plays only 17. Fewer games mean less opportunity for skill to separate from noise — raising the NFL's luck contribution.
Leagues without strict salary caps (like European football) let wealthy clubs hoard talent. This amplifies skill differences — lowering apparent luck in leagues like the Premier League.
LoL (23% luck) is more skill-driven than MLB or La Liga. Structured league formats and best-of series help the best teams rise. Dota 2's higher variance (34%) reflects its comeback mechanics.
Sports exist on a vast spectrum. Here's how our leagues compare to activities at the extremes.