BOSTON - The Celtics -- already mired in a three-game losing streak, and having lost eight of their past 11 games -- found themselves down 18-4 five minutes into Friday night's game against the Indiana Pacers. It was the kind of performance that, had fans been allowed into TD Garden, would've been met with a hearty round of boos. But rather than resigning himself, and his team, to another ugly loss in a stretch full of them, Kemba Walker put the Celtics on