Because of the 9-team schedule format, Boston played 12 games against Eastern opponents and 8–10 games against Western teams:

• Wayne Embry (CIN): 12 games
• Walt Bellamy (BAL): 10 games
• Zelmo Beaty (STL): 9 games
• Wilt Chamberlain & Nate Thurmond (SFO): 8 games

That’s 39 of 80 regular-season games. Then the Celtics played all 10 playoff games against Hall of Fame centers (five against Cincy, then five more against Wilt & Thurmond).

Two years later the Celtics played 10 games each against Eastern rivals (Knicks, 76ers, Royals) and 8–10 games against Western teams. So here’s who Russell faced that year:

• Wilt Chamberlain (PHI): 10 games
• Willis Reed (NYK): 10 games
• Wayne Embry (CIN): 10 games
• Nate Thurmond (SFW): 9 games
• Zelmo Beaty (STL): 9 games

That’s 48 out of 80 games against Hall of Fame centers. They then played 10 of 17 playoff games against Hall of Fame centers.

Data from basketball-reference and Backpicks Top 40.

EDIT: And yeah this is because every Russell thread is immediately inundated with “there were only 10 teams!” Yeah man, and half of them had Hall of Fame centers that he destroyed. From Backpicks:

“All of these players declined in efficiency, and only Thurmond improved his scoring (although on dreadful accuracy). Willis Reed and Zelmo Beaty were vaporized by Russell. The numbers are particularly compelling because, unlike today, Russell played most of the game and Boston did not double-team frequently.”