[OC] Ranking Every NBA Championship by the Difficulty of the Opponents Faced
I ranked every NBA championship from the most difficult path to the easiest using Simple Rating System, or SRS from Basketball-Reference.
SRS combines a team’s average point differential with its strength of schedule. A team with a +6 SRS was approximately six points per game better than an average NBA team during the regular season.
To make every championship path directly comparable, I replaced each actual champion with the exact same hypothetical team.
That standardized team has an SRS of 6.11, the average SRS of a championship team.
For each series, I converted the difference between the standardized champion’s SRS and the opponent’s SRS into a game-level win probability using the SRS win-probability formula developed by Basketball-Reference founder Justin Kubatko:
Home win probability =
1 / (1 + e^-[0.613230 + 0.167546 × (Home SRS - Away SRS)])
source for Srs top 100: https://www.basketball-reference.com/tools/share.fcgi?id=k3YK6
The 1972 Lakers faced three opponents:
| Opponent | SRS | Standardized series win probability |
|---|---|---|
| Chicago Bulls | +7.91 | 39.30% |
| Milwaukee Bucks | +10.70 | 18.97% |
| New York Knicks | +2.28 | 83.05% |
Multiplying those probabilities:
0.3930 × 0.1897 × 0.8305 = 0.0619
The average championship-level team would have only a 6.19% chance of defeating all three opponents.
Milwaukee was the largest obstacle. The defending champion Bucks went 63-19 and recorded a +10.70 SRS, one of the strongest marks in league history.
Before facing Milwaukee, Los Angeles also had to beat a Chicago team with a +7.91 SRS. The Lakers then defeated the Knicks in the Finals.
The 1995 Rockets faced:
| Opponent | SRS | Standardized series win probability |
|---|---|---|
| Utah Jazz | +7.76 | 40.57% |
| Phoenix Suns | +3.86 | 73.08% |
| San Antonio Spurs | +5.90 | 56.74% |
| Orlando Magic | +6.44 | 52.04% |
Their complete path probability was:
0.4057 × 0.7308 × 0.5674 × 0.5204 = 0.0875
That gives the standardized champion an 8.75% chance of surviving Houston’s path.
Houston did not merely defeat one historically great opponent. Every team it faced won at least 57 games:
Cleveland faced:
| Opponent | SRS |
|---|---|
| Detroit Pistons | +0.43 |
| Atlanta Hawks | +3.49 |
| Toronto Raptors | +4.08 |
| Golden State Warriors | +10.38 |
The first three rounds were relatively manageable for an average championship team. Golden State was the enormous exception.
The 73-win Warriors were strong enough to move Cleveland’s total path probability down to 10.30%, the third-hardest path in the rankings.
Chicago’s six championships rank:
1997 especially was a lot of tough opponents.
Although every individual series was standardized as best-of-seven, I did not invent additional playoff rounds for champions who only needed to defeat two or three opponents under the league structure of their era.
A team facing two opponents will generally have a higher probability of completing its path than a team facing four opponents.
It would be possible to compare the average difficulty per series instead, but that would answer a different question. This ranking measures the difficulty of completing the entire championship path that actually existed.
I would have thrown out the old years for aesthetics, but I kept for the sake of completion.