I have seen “With on-pitch team possession statistics from some of the Big 6 clubs increasingly reaching 70% and more, is this the game that fans really want?” quoted a lot recently as an indicator of the growing disparity between to side. I think a large part of this is a change in tactics to a possession game from a counter punching game, it may be an indicator but it is over simple to us it in isolation.
It's only natural with so many defensive minded managers that are happy to concede possession and wait for a set piece opportunity.