Bill Russell averaged 24.1 rebounds per game and anchored a tough Celtic defense.
With the retirements of guards Bob Cousy and Bill Sharman and the emergence of K.C. Jones and Sam Jones as the new backcourt tandem in Boston, defense became more important than ever to the Celtics' success. The Celtics still ran the ball, but with K.C. Jones at the helm instead of the master, Cousy, it was a more cautious fast break. Jones also wasn't the scorer Cousy was, but he made up for it with tenacious pressure defense that rattled opponents and set the tone for those Celtics. With Bill Russell at center, Tom "Satch" Sanders at power forward, the ball-hawking K.C. Jones at one guard and under-rated defender Sam Jones at the other backcourt spot, the Celtics led the NBA by allowing just 104.5 ppg. And they did it without slowing the pace of the game, as their 112.8 ppg scoring average attests.

The Celtics dedicated the 1964-65 season to the memory of Walter Brown, the team's founder and owner who had passed away before the start of the season. They jumped out of the gate with 11 straight wins and went on to post what was then an NBA-high 62 victories, 14 more than Eastern Division runnerup Cincinnati and 13 more than Western Division leader Los Angeles.

Sam Jones led the Celtics with a career-high 25.9 ppg, fourth in the league behind Wilt Chamberlain, Jerry West and Oscar Robertson. Sixth man John Havlicek was next at 18.3 ppg, but it was defense and depth that set the Celtics apart from the field. With a bench that featured the versatile Havlicek, veteran forward Willie Naulls, guard Larry Siegfried and backup center John Thompson (who would go on to coaching fame at Georgetown), Coach Red Auerbach could afford to rest his starters and keep them fresh as needed.

Though the Celtics romped through the regular season, the picture was muddled by the midseason trade that brought Wilt Chamberlain back to Philadelphia from San Francisco. Suddenly the 76ers were a challenger to Boston's dominance. They played much better in the second half of the season, knocked off Cincinnati in the first round of the playoffs and gave Boston all it could handle in a seven-game Eastern Division Finals that wasn't decided until the closing seconds of Game 7. That was when, with Boston clinging to a 110-109 lead, Philadelphia's Hal Greer threw an inbounds pass that was tipped by Havlicek to teammate Sam Jones, who dribbled out the clock. That, of course, produced the most famous radio call in basketball history, Johnny Most's gravel-voiced "Havlicek stole the ball!" In the NBA Finals, the Celtics cruised past a Lakers team depleted by the loss of Elgin Baylor to a knee injury, winning in five games. They set the tone by winning the opener by a lopsided 142-110 margin, and wrapped it up with another one-sided win, 129-96, for their seventh championship in a row.