1950s superstar Bob Cousy had retired, yet Red Auerbach's club barely slowed down with his absence.
While Boston could surely still pass and score, it was their defensive emergence, led by the incredible Russell, that was now leading a streak of NBA titles.
Russell led the league in rebounds and was one of two high-volume shot blockers dominating the NBA.
Auerbach's sixth man, John Havlicek, was the team's leading scorer at 20 per game.
This combination of active defense and unselfish shooting got Boston a league-high 59 wins in 80 NBA games.