NBA Finals: Celtics take season’s worth of lessons into Game 5

BOSTON — The Celtics picked the most inopportune time to play their worst game of the season. Boston’s 122-84 Game 4 loss to Dallas in the NBA Finals had all kinds of superlatives, and none of them were good. It ended the Celtics’ 10-game playoff win streak. It was the Celtics’ lowest scoring output of