I think our leagues never had as much strength in depth as it does now.
Other leagues certainly lack something in comparison, outside of the top clubs, hence why English clubs do so well in European competitions. Even rubbish like Celtic and Rangers did well in the Europa league this year.
I personally think more individual errors in our league is caused by the quality that players play against week in week out, it never really lets off. There are no free weeks, unlike in other leagues and I also put some of it down to the intensity inside the stadiums, no matter who is playing. Again, this never lets off.