About Champs by Chance
Winning
a championship is difficult. While many factors contribute to a team ultimately
hoisting a trophy, not all competitive environments are created equal. One of
the most important structural factors is simply league size. As of 2025, the
four major American professional sports leagues (NBA (30 teams), NFL (32
teams), NHL (32 teams), and MLB (30 teams)) are similar in size. Historically,
however, league sizes have varied dramatically. The NBA had as few as eight
teams in the 1950s, the NFL had eight teams in 1943, the NHL had only four
teams in the 1920s, and MLB operated with 16 teams for the first 61 seasons of
the 20th century.
Fans
often grow frustrated when their team fails to win a championship, and even
more so when that drought stretches for decades. But how warranted is that
frustration? And how fair is it to compare championships across eras when the
competitive landscape was dramatically different? Winning one title in a 30 or
32 team league is fundamentally different from winning one in an eight-team
league. The psychology of fandom also varies. Supporters of consistently poor
teams may lower their expectations, while fans of perennial contenders may
experience repeated heartbreak after falling just short.
This
site takes a different perspective. Rather than focusing on team quality,
player talent, or front office decisions, we examine championship probabilities
purely from a structural standpoint. For the purposes of these calculations,
every team is assumed to have equal ability, and each game is treated as a
50/50 proposition. Under this assumption, it may seem intuitive that each
team’s championship probability in a given season is
simply one divided by the number of teams in the league. In
reality, the calculation is more nuanced and depends heavily on league
structure — including divisions, conferences, and playoff qualification rules.
Consider
MLB from 2000–2012. During this period, each league sent three division winners
and one wild card team to the playoffs. However, divisions were not uniform in
size: most had five teams, but the AL West had four teams
and the NL Central had six. Assuming equal team strength, a team in the AL West
had a 25.0% chance of winning its division, while a team in the NL Central had
only a 16.7% chance. Teams in five-team divisions had a 20.0% chance. These structural
differences materially affect postseason access and, ultimately, championship
probability.
After
accounting for both division-winning probabilities and the more complex calculation of earning a wild card
berth, and then modeling advancement through the playoffs, the per-season
championship probabilities were 3.91% for AL West teams, 2.93% for NL Central
teams, and 3.44% for teams in five-team divisions. While these differences may
appear small in a single season, they compound over time. Across the 13 seasons
from 2000–2012, the probability of winning at least one championship was 40.5%
for AL West teams, 32.1% for NL Central teams, and 36.5% for teams in five-team
divisions.
Small
structural advantage, repeated year after year, can
meaningfully shift long-term outcomes.
On
this site, we focus on three primary milestones:
- The
probability of making the playoffs
- The
probability of reaching the championship game or series
- The probability
of winning a championship
Our
emphasis is on cumulative probabilities over meaningful periods of time, while
grounding all calculations in the specific league and playoff formats in place
for each individual season.
Future Projects
Repeat
all analyses using simulations based on how good a team was each year
Add
other sports and/or leagues such as MLS and WNBA
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