Today I watched the highlights of the game and yes, Granada looked very good, but what kind of strength are you talking about? The team is in 19th place and has 13 points from 24 games. This is the obvious outsider. The problem is Barcelona - they have a terrible defense (Granada could have scored more) and against its background even teams like Granada look dangerous.
You can be 95% sure that Athletic will win against Almeria today (the team has 6 points and 17 defeats lol) and so it turns out that we will have an interesting fight for the top 4 where Barcelona will not be safe at all.
I saw that it wasn't Granada who played well but the Barcelona team played badly so the game between the two teams was quite even.
It's a shame about the performance of the Barcelona team in this match, in fact they have strong strengths this season, but the consistency of the Barcelona team's play is very inconsistent, making them often lose important points that should be maximized.
The competition for the top 4 positions in the La Liga standings is quite fierce and in fact I think Barcelona will probably not be able to finish in the top 4 positions in the final La Liga standings this season because they cannot be consistent.