It could be that but these are guys who have own World Cups, Euro Championships and Champions Leagues. They are some of the best players ever in a system that was one of the best ever. I think it is a couple of things. Firstly Real players seem shattered, not just the Spanish but Ronaldo and Coentrao are both injured too. They've had a massive season with 2 cup wins and a full league season. Barcelona have looked jaded all season with even Messi looking human.
Also on the tactic it's like any big change (Ajax and total football or Bayern's attacking sweeper system as examples or more recently Barcelona) eventually other teams work out weaknesses. That's what good coaches do. How often have we seen a poor side come into the Prem and ' take everyone by surprise' and stay up for a season only to get destroyed the next? Hull were a good example under Phil Brown. I think Spain just needed to evolve more quickly.