I think the top lines and PP1 haven't been changed yet because of the difference between practice/preseason and real games.
The PP1 squad may be looking great during practice: give them a few real games to see how they do before shuffling.
Some of the top players have looked slow in preseason/practice: give them a few real games to see if it was just 'vet privilege' or a real issue.
Some forward pairings look a bit off: give them a few games to see where the problem (if any) is.
You get a much better sense of what works or doesn't work by watching real games against real opponents (does Montreal count?)
We've got new coaches. I don't mind them taking a few regular season games before doing a lot of changes. If there's still no improvement after maybe 10 games I'll start worrying.
We have seen large improvement in overall play, mainly because of the new players/pairings/lines beyond the 'top 6', so I'm reasonably happy with both Tre and Berube so far.