This.
A lot of our players simply do not posses enough quality to be able to coast through games. Whenever a number of our players aren't absolutely 100% 'on it', we struggle against pretty much anyone we play against.
I honestly don't think it's much to do with mentality, I think Poch has genuinely made the likes of Trippier, Davies, Dier, Sissoko etc believe they are good enough to compete, but that doesn't mean that in the cold light of day they actually are.
If any if our players think they can "coast" through games that's it's own fundamental issue right there; independent of any notion of "good enough".