Let's roll the clock back to 2008
- Manchester United have just won the Champions League but England have failed to reach the Euros.
- English clubs are easily the best in Europe, with 3 out of 4 semi finalists in 2007 and 2008 (and 2009). In fact in 2008, no England club was knocked out by any other nationality of club.
Then Spain win the Euros in summer 2008. Barcelona win everything in existence in 2009. Spain win the World Cup in 2010. Barcelona win everything in existence in 2011. Spain win Euro 2012. Madrid and Madrid compete for the 2014 Champions League and Barcelona win nearly everything in existence in 2015...
I think there are two factors at play. First, Spain basically have a fantastic group of Spaniards at every age level. A Spanish XI of players based NOT in Spain would probably destroy any English XI you put out.
Secondly, just like Arsenal raised the bar with the Invisibles and Chelsea raised the bar further with the record breakers, and United met the challenge with the European Double winners.. there is a case of teams competing and out competing each other, which raises the standard of the whole league. When you've been playing super-Barcelona and Real Madrid at least 4 times a year for the past 8 years, the league improves. Atletico Madrid gave them a go. A few other clubs might raise their game to compete.
I dont think you can have use excuses other than to say Spanish football is pretty good right now.
Edit:
Oh, and after the Invicibles (2004), the Record-Breakers (2005) and the European Double Winners (2008), English football didn't push on. United lost Ronaldo and regressed slowly, slowly, then quickly. Chelsea lost Mourinho and regressed slowly, slowly then quickly. Arsenal gave up trying to win titles. Liverpool bought Andy Carroll. City have never truly pushed the league on.