One of the early chapters in Coach Speak 101 says something about how games aren't won or lost in the first quarter.
Maybe they aren't, but dig yourself too big a ditch, and you'll bury any hope of winning.
Lately, the Celtics have been at their worst in the first half of games. Opponents are averaging 58 points in the first half against Boston, since Jan. 1. During that span, they are also allowing opponents to shoot 53.1 percent from the field and an impressive 48.6 percent on threes.
Teams have been especially effective in utilizing pick-and-roll plays, a staple of every team's playbook for easy scores.
"It goes back to the presence on the ball," said Celtics head coach Brad Stevens. "Were going to have to get better at it. We really have defended it well at times. But we're going through a stretch where we're not defending it well."
But those defensive successes are nowhere to be found now with the Celtics looking very little like the team that ranked among the league's best in several defensive categories. Before Jan. 1, teams were averaging 47.3 points scored in the first half against Boston and were limited to 44.3 percent shooting overall and 32.3 percent on threes.
Effort and execution more than anything else, is what the Celtics desperately need to do a better job during this period of struggle.
"We're not getting back on defense," said Boston's Jordan Crawford. "We're not playing hard enough."
And that has taken one of the surprisingly solid teams defensively at the start of the season, and transformed them into a squad that has given up back-to-back season highs for points allowed.
Sadly, that is becoming the narrative for a Celtics team that's coming up on the halfway point in the season.