What the Celtics must do in Game 3: Do not repeat Game 2′s subpar shooting performance

The Boston Celtics host the Cleveland Cavaliers in Game 2 of the second round of the NBA Eastern Conference Playoffs. (Barry Chin/Globe Staff)The NBA, as the last coach to lead the Celtics to an NBA championship liked to say and say often, is a make-or-miss league.

It can sound trite or simplistic, that old Doc Rivers line. It can sound suspiciously like an excuse. It also happens to be true.

Sometimes your five are missing and missing, and their five are making and making, and there’s not a thing Red Auerbach in his prime or any other coach worth his clipboard can do to keep the gap from widening on the scoreboard.

It happens, those rare and lousy nights at TD Garden when the rim is kind only…