It's a bit of everything. Oline is struggling with stunts, as well as blocking for the zone runs. The backs are struggling to find the holes and make the right cuts - Shady isn't a great fit for this it seems like. We had a lot of success in shotgun last season as it deepens the pocket, and allows us to run more read option concepts. We're now majority under center unless its an obvious passing play it seems.
I think some quick hitters from peterson will do the offense good. Shorter 3rd downs can create easier mis matches, and force the linebackers to shorten their depth. This can create some big plays which have been lacking.
Last week on 3rd and 14 there wasn't a non-rushing saint within 10 yards of the LOS. So you have 7 guys back there covering the sticks making checkdowns the only options.