You guys have to remember that even the #2 WR on teams is now being covered by Bly, another darn good CB.
With Bailey, Bly, and Lynch in the secondary you will see many passing games shut down by Denver this year, and that's exactly why I picked them as my defense. Teams will have to run to beat them.
Now, if the WRs name is Harrison, S. Smith, Holt, etc you never sit them regardless. However, as the original poster asked, if the WR is a semi stud like Colston, Burress, etc I most definitely sit them assuming I have a better option.