percentage for how much responsibility the Defense has on the Offense I would put it at MAYBE 5%, with that almost solely being because of ASFP. It is not THE factor, or even a top 5 factor, for why our O is bad. It's not like the O is starting every drive at their own 10. Conversely, how many of the D's drives have started with terrible ASFP? They can't do as much when the O isn't driving the opponent to the other end of the field.
I'd be curious to see the analytical breakdown for the O's performance based on ASFP (ie. points scored when starting from "X" yard line, # of 3 & outs, etc). My guess is we won't see a major statistical difference in the O's performance when starting from the 25 or the 40. You might see a dip when starting from inside the 20 but that would probably be in line with national averages (that's my assumption at least).
Yes, the D doesn't help the O with ASFP, but ASFP doesn't win games points do. This D is giving the O a chance but the O isn't doing enough to win.