Barcelona were more at the middle, not too good performance but also not bad for a team with young players who are still in the beginning of building their carrier except for Lewandowski who already knows more about the game. Barcelona players needs a lot of game time to be able to understand the game better, this coming season might be something different to watch. Last season there was no competition for the La Liga, checking the points difference between Madrid and Barcelona is too wide, which makes Barcelona performance look poor.
Next season, Real Madrid will also have a more fierce and fierce squad, so this will also prevent Barcelona from challenging for the title in La Liga again. Even though the facts you say don't rule out the possibility that Barcelona will be much better than this season. Because apart from there being still many young players in Barcelona, the team will also be trained by a new coach who may have new methods that will be implemented in the Barcelona squad later.
They may attempt to compete with Madrid but the odds for them having a close range competition is rare. Changing their coach means adapting to new style of play and it takes a while to be much effective on the field, during those process Madrid will be accumulating more points before Barcelona will get back to form to raise the competition. Barcelona will definitely improve, same way Madrid are also improving from their own ends.