Don Nelson, second-winningest NBA coach who won 5 titles as a Celtics player, dies at 86NBA: Boston Celtics, Graphic (Photo By: NBA / MGN)(AP) — Don Nelson, the second-winningest coach in NBA history who won five championships as a player with the Boston Celtics, died Sunday. “On Sunday morning our beloved husband, dad, grandfather and great-grandfather Don Nelson peacefully went to be with the Lord, surrounded by his loving family,” the statement said. “Don Nelson was a true innovator whose influence on the game of basketball is still felt today,” current Warriors coach Steve Kerr said. In his final season as a coach, Nelson mentored rookie Stephen Curry in 2009-10. “One of the big reasons I was drafted by the Warriors was because of Don Nelson.