The EPL style is fast and physical moreso than the other leagues. This generally means that the EPL needs players already physically ready or technically competent to make up for their individual lack of physicality.
I.e. the EPL does not have time to nurture players and they want the finished product.
The other leagues know this, and the clubs nurture players until they can maximise profits via a sale to an EPL club.
An example from a Lazio fan's point of view is Wesley Hoedt.
Signed from AZ Alkmaar as a free transfer in 2015.
Just because two English teams choked, it doesn't mean the league is falling behind the other big leagues.
Man Utd would have probably won if Mou hadn't played a bland, soulless brand of football. As for Tottenham they might have had a chance if they didn't celebrate a 2-2 draw at Turin like they had already won the champions league.
Fact is the two best English teams are still in it and Chelsea could be too (all be it unlikely)
3 Spanish (will be 2 if Chelsea win)
2 English (will be 3 if Chelsea win)
1 German (likely)
The English clubs are pretty fairly represented are they not?
I think the main issue is that the 2 best players of this generation have chosen to play in Spain and the best national team of this generation is Spain and as a result the UCL has been dominated in recent times by Spain.