I think you can see it in 2 ways....one is that when Spanish teams are up for it in their heads, they are the best...which is why they are doing so well in the CL. But the problem with Spanish teams is attitude. Against smaller teams they can't be bothered.
Anyteam that wins the league this year can be considered rather substandard, esp if Depor win it (Arsenal thrashed them 5-1 at a time when the Gunners were in crisis). Usually when we talk about winning your home games and hoping to get something from your away games, we talk about avoiding relegation. But in Spain, that is a fomula to win the league itself!
Juve and Man Utd for instance, have the right attitude towards everygame...that is why they lose so few games. Chances are, if Depor win it, they will flop next year...that shows they are not a great side if they indeed fail next year. Barca and Real will not even make 5th place in England or Italy this year...not because lack of quality but because of lack of attitude. Man Utd, Arsenal, Juve, Lazio will always be there at the top of their leagues, gaining at least 75 points each.