Girona's quality may only be good for La Liga and to measure how well they can manage their busy competition schedule they will have to try to get a place in the champions league next season. I agree that every team must have reserve players who are as good as the main players and that is what Real Madrid and Barcelona currently have, so however, Girona, with the depth of their current squad, I don't think can match these two teams in the title race. Being able to finish in the top 4 is a very realistic thing for them.
Girona may not appear to be a good contender against bother teams which you did mentioned but I'm very optimistic that with the recent form and performance of Barcelona, Girona is sure going to give them a tough time winning this match by weekend except Barcelona would have improved or come up with a better tactics which will definitely help them out.
Giron this season is so focused and really bent on winning the league title if given the chance, but most definitely Real Madrid will be a stumbling block because they will need the extraordinary to get pass Real Madrid, as Madrid is not in anyway giving them a chance although at this point the only have a few goals keeping them apart as they have the same point on the table but after the match against Barcelona we would see if Girona would be a to prove themselves fit enough to contend against Madrid in the nearest future for the league title.
A tough time for sure, because Girona has excellent high pace attacks and Barcelona is more vulnerable this season than they were last season. I don't know if everyone recalls this, but last season Barcelona was remarkable defensively. I think this is their weak point while their offense is also not that impressive. But I didn't expect them to win the game against Atletico, I was more leaning towards a draw between the two teams, but in the end it is still Barcelona and at home they can still beat any team.