They most definitely won the game at the three point line. I don't see how you can refute that. It's not that they took bad shots - most shots they got were pretty damn good, but they attempted about 30 3-pointers and made 14 or 15. The ball movement was very good (aside from quite a few really silly turnovers, but they kept those at an overall managable number) and they did plenty of good things, but they got no interior scoring from Diaw/Duncan/Tiago and that 3 ball made everything go.
Not necessarily a bad thing, but if your starting PF/C comine for 7 points on 30% FG, the 3-ball is definitely a saving grace.