I can't be arsed to get in the debate proper but I'd say that "backing off" as a style of defending in itself is very vague isn't in itself a problem. Its how its done that is the issue. Rio at his peak was a master of just letting the attacker run and run, narrowing their options as they go. But its knowing when to step up and how to step up that is the issue. Small detail in the style which is going to separate good from bad, but can obviously be covered or exacerbated by style of the team and partner.
I wouldn't actually blame Cahill for the Ade goal at all, the main threat there is to strike before the defence is set so I can see why they are keen to get deep and that line established. 9/10 Ade misses that or Cech saves, and he's hardly a Gerrard who you'd back to have a go from there.