Bit of both. It's a reflection of the structural inequality. City are good but the other big teams are in transition. The rest (i.e. Leicester as the best and everyone from Everton below) have had 30 years of the top four being massively rewarded financially for getting into Europe and it shows. In the 'old days' I think the entire league was much more compressed in terms of ability and finance so I'd argue, it's easier these days to be miles ahead.
They are very good though. Very, very good. Just don't tell them.