That's an insult to Atletico Madrid and Sevilla, comparing Burnley to Atletico Madrid is rubbish cos Burnley are not known internationally and have been in the league for two years, Atletico Madrid has been in top 3 sides constantly. Players from Spurs, Chelsea, Man United, Man City, Arsenal and Liverpool are more known than La Liga's top 6 sides (Real Madrid, Barcelona, Atletico Madrid, Sevilla, Valencia and Villarreal), lets exclude Barcelona, Real Madrid and Atletico Madrid that is equivalent to City, United and Chelsea in quality level of league, now do you think people could easily name players from Sevilla, Valencia and Villarreal more than Arsenal, Liverpool and Spurs when EPL is most viewed league in world? Depend on who watch La Liga or EPL.
Competitive of league level between La Liga and Premier League spread 5 seasons from 2012-17, how many teams have finished in top 3 sides? La Liga has Real Madrid, Barcelona and Atletico Madrid finishing in top 3 places for 5 years, EPL has City, United, Spurs, Liverpool, Arsenal, Chelsea and Leicester City finishing in top 3 places.
Quality of the league sides level, it's not surprising that Barcelona and Real Madrid have been stronger than EPL teams for 5 seasons since 2012 but comparing between La Liga and EPL for 3rd or 4th to bottom 20th placed, EPL is much stronger than La Liga in this which give EPL top sides bit of trouble, it also helped to strengthen City and United now.
Real Madrid has dropped a bit in quality level, not much about Atletico Madrid that had Chelsea and Roma in groups stages, in any other group stage Atletico Madrid would go through. Barcelona has dropped a bit in quality level since departure of Neymar
it's not the improvement of competitiveness has taken its toll on Barcelona or Real Madrid. Barcelona are going similar path as Manchester United since departure of Ronaldo but Barcelona will avoid the same path as ageing United in 2013 because they are going to spend a lot of money on new players before its too late, United didn't do that in 2009-2013, as a result, United gotten older and collapsed quickly. Real Madrid is getting older that has Ronaldo, Ramos, Modric, Navas in 30s and Bale, Benzema and Marcelo entering into 30s.