Celtics are NBA’s best team because of all the little things, which could be the key come June

LOS ANGELES — The Boston Celtics have been mainstays near the top of the Eastern Conference for nearly a decade, but breaking through and becoming champions is a barrier they’ve yet to cross — so many iterations of teams who’ve contended in the Jayson Tatum era. This version feels a little different, even if they still dance with volatility every now and again, even if they show signs of combustion in moments of truth. The Celtics didn’t play their best game against the Lakers on Christmas Day, but one thing is for certain: Their best game is better than anyone’s best game so far this season. That hasn’t always been the case over the last six years, but it definitively…