I look at it this way. There are exactly zero perfect FBs, they are expected to be brilliant in defence and never allow a cross in, never get caught out of position, defend every corner perfectly, speed like a gazelle down the wing (since many teams don't use wingers now), dazzle the opposition defence with their attacking prowess, deliver perfect cross after perfect cross .. and even get on the end of a few themselves to contribute to the goal tally .... ta raaaaa !!
Well there isn't a FB alive capable of that lot or even close. So I expect mistakes, every player makes them but generally fans give midfielders and attackers more leeway than defenders.
I think Enrique does pretty damn well most of the time and can forgive him the occasional brain-fart. Spend a lot, and I mean a lot, and we could get better but in the meantime I'm thankful that we have him after some of the dross of the past decade and if I want to point fingers then there are other players/positions that deserve that attention far more than Enrique (and Johnson for that matter).
Oh and he does actually look like he gives a damn and gives his all, I like that, Liverpool fans have always supported players who give their all. Don't understand the knockers.
Anyway just IMHO 🙂