In theory, if you're consistently outplaying the opposition then you tend to win far more games than you don't. You can always get bad luck, especially against other teams, but over the long run you win out. Unless you're extremely unlucky.
That's been the driving factor in our league successes under Pep. We're consistently better than the weaker teams, so we almost always beat them and build up these impressive win streaks in the process. That's why when we play well but drop points to weaker sides in the past, it was never too concerning. Because you know that in the future the results will start to be fairer to the performances.
What's interesting in the past week is that we went away to three of the most in form and strongest teams in Europe, all back to back, and for the most part outplayed them all fairly notably. If we play like that against every big side we face this season (without having to worry about playing them all away consecutively) then we're in for a great time. This is a new development too. We've never really dominated teams this good in this way before so consistently.
As for the results, only the PSG one is disappointing. But thankfully it's the most likely to be insignificant in the long run.