I think some of you are giving Moss a little too much credit and Q not enough.
Sure, Moss helped take a little bit of pressure off the run but it was pretty apparent, even a couple games into the season, that he did not have the elite speed that he used to and the DC's adjusted to this. So I'm not 100% sold that his presence on the field greatly improved our run offense by loosening up the box.
Most of Moss's contributions came in the mentoring of our younger receivers. IMO, Boldin can fill that role, as well as producing much more on the field. I really think that the addition of Boldin has already greatly improved our WR position. Only time will tell but hopefully I'm right .