THERE IT WAS, on page one for all to see and judge, the unpleasant story of a fallen hero: John Lucas--enormously popular All-America basketball star at the University of Maryland in 1976, role model for so many downtown playground kids over the years and now "back home" with the Washington Bullets--admitting a cocaine habit that could end his career. Why does someone like this--with fame, fortune and the talent to stay on top in the toughest basketball courts in the land-- end up on the skids in the court of last resort?

Understanding may not come easily or at all to those whose families include no popular personalities rich enough to toss out $100 a gram for cocaine, or whose lives do not even touch the glamor that America's sports fans attach to the top professional athletes. Besides, when a guy has the world at his fingertips and blows it this badly, isn't he just a loser who deserves to be drummed out of the corps?

True, and that could still happen; after all, the Bullets and the National Basketball Association are businesses, and Mr. Lucas could run himself right out of the sport for good. But in being forced to face up to his problem publicly, perhaps Mr. Lucas has touched a chord here and there among those whose personal or family trials have included battles against other drugs, or alcohol or gambling--struggles that for any number of reasons transcend income, intelligence, talent or attractive opportunities.

Maybe that is why so many of us are pulling for John Lucas to win this contest--and why, when he stepped on the Capital Centre court Wednesday, there were no boos, only cheers and yells of "Let's go, Luke." That has to help, as does support from the Bullets and a serious rehabilitation program. But the biggest help for Mr. Lucas now has to come from himself, under pressure. "I've tried before," he told Post staff writer David DuPree, "but now I have no choice. Everything I ever stood for is at stake."

That is the score at this point--and with a home crowd rooting for victory, John Lucas can set another good example for those who looked to him before all this to do just that.