Two-time NBA champion Isiah Thomas explains why, for this group of Celtics, mental lapses can arise during low-stakes games.

The Boston Celtics don't like to lose ... Boston finished 40-42 behind the efforts of then-rising All-Star point guard Isaiah Thomas and saw themselves swept by the East's eventual NBA Finals ...

Isaiah Thomas becomes just the fourth Celtic in franchise history record a 50-point playoff game, scoring 29 points in the fourth quarter and overtime to win this thriller over John Wall and the ...