No no, I agree La Liga has declined. What I am trying to say is, it is not like because of the decline any of the top teams from other european leagues like Inter Milan or Bayern Munich etc will be confidently taking on the la liga teams or beating them easily.
Regarding competition in the leagues, I agree there. Competition in La liga has always been much less than that of the premier league. But you can't say it is less than the Bundesliga where Bayern won the league for 11 years in a row. Or in Serie A where Juventus won 9 years in a row. Bundesliga this season is different so far - but I think eventually Bayern will win it, again.
I have seen the stats in your post and I see your point, but objectively speaking every single one of these big teams would rather not face any of the spanish sides for as long as possible in the tournament.
All 4 la liga teams proceeded as group champions.
Whereas from the most competitive league in the world, only 2 teams proceeded to the next round. Newcastle had a tough group sure, but Man united?
The 3 Italian teams that went through were all group runner ups and who were the group champions in their groups? A spanish team, in all 3 of their groups.
So to sum it up, despite declining La Liga, the rest of the european leagues have also declined and no one except Man City can actually take on any team easily.
RE: Who is to Blame?