Meanings of own mediocrity in English

His own mediocrity enrages him while the success of others fills him with dismay.

A few discovered their own mediocrity, and this was the cruellest discovery of all.

And so we may comfort ourselves, in our own mediocrity and laziness, by denying the existence of all greatness and goodness.

To excuse our own mediocrity we call the man who tries to get out of the rut a "blasphemer."

Theirs was the energy, the conviction, the motivation while the Premier League holders spluttered in disbelief, struggling to comprehend their own mediocrity.

Their list for the 2019 Elections features implicated ministers and, apparently, too many "old faces" wallowing in their own mediocrity.