For the answer to this, take a look at stats from the past. How often do studs actually sit out games when they are listed as probable, questionable, doubtful, etc? Just to give you some sort of reference, in my league, here are the top 10 at each position who have missed at least one game:
QB - none. The highest QB to miss a game is McNabb, at QB14
RB - Westbrook (1), AP (2), Addai (1), Lewis (1)
WR - Fitz (1). Only other WR in the top 20 to miss a game was when Jennings missed the first 2 games of the season.
TE - Dallas Clark (1)
K - none. The highest K to miss a game is Morten Anderson, at K27
D- none, obviously
So, of the top 10 at each of the 6 positions through 13 weeks, a total of 7 games were missed (5 by RB's, 1 by WR, and 1 by TE). And that's out of a possible 780 starts (6 positions x top 10, x 13 weeks). And, of those 7 games that were missed, how many were already declared out before gametime? All 7, if I recall correctly.