What makes the bills a “soft” team is their philosophy (imo). They play a pass first offense combined with a zone defense. they essentially say we’re going to get a lead and you won’t be able to catch us.
this has/can work but isn’t the same as a “we’re going to run the ball and you can’t stop us”philosophy. Teams that successfully operate this philosophy typically combine it with an aggressive defense.
the bills style is dependent on their passing game being successful. Passing is, on its face, more dependent on other factors than running. E.g. precipitation, wind, timing, the day, specific matchups etc.