Of course there is no guarantee for any team in the league to have a wonderful season. Consistency is key for the teams fighting for the league title. For example I assume most of us expected a comfortable win from Barcelona against Vallecano. Their performance was very impressive to do so as well but Vallecano were lucky to get one point anyway. This kind of results are a part of football. However hopefully they shouldn't have the same incident against Valladolid as well.
You said it right and yes I agree with you. All teams hope to get maximum points from each match but they can't do anything when their opponent is a big team with better quality players. The only way out is to focus players on defense and prevent more attacks from the opponent until the end of the match while taking advantage counter attacks.
This strategy is widely adopted by mid-table and lower-level team coaches to get points. But I wouldn't say everything will work out when top teams are able to explore mistakes made in defense to score goals. I also hope that the same situation will not be experienced by Barcelona in the next match, especially after they won the match against Sociedad with convincing score.