Indeed if you look at the snaps that Welker missed because Edelman was preferred to him it works out at 16% of offensive snaps. Welker averaged 11% of snaps off the field in 2011, and well over 20% in both 2009 and 2010. Edelman might be the player picking up the snaps that Welker is spending off the field, but there is nothing to suggest that spending those snaps off the field is unusual for him.