In the universe of professional basketball, the little things are numerous and vast. Proper spacing on an inbound play, say, or ducking under a screen instead of fighting over the top of it and watching one of the best 3-point shooters in the business get a clean look with a half minute left. Little things. When the Celtics win games, the little things don’t seem so obvious. A five-minute stretch where they suddenly, and without warning, abandon their offensive principles and being playing a series of one-one-one games?