Most Celtics losses have come off back-to-backs and they have played well against elite teams home or away. Besides, Kendrick Perkins has just about returned from a long layoff. Shaq is again yo-yo with his injuries and Jermaine O'Neal is expectedly out with injury. Delonte West is also yet to get back to the rotation while Marquis Daniels has been injured and is out. So essentially, they are not fully healthy.
I hate the Celtics' current trash-talking, badly behaving squad and would root for it to lose, but one must admit that they provide the biggest challenge to the Spurs with their depth, their defensive prowess and team effort. Yeah, even bigger than the Lakers, as of now.