Our issue last season was conceding silly goals to weaker teams (United had 44 GA, Liv 42, Chels 36, City 32 - made worse when you think Liverpool shipped 7 goals in one game/CB injuries and Chelsea did really poorly under Lampard). This year we've only dropped a couple of points at Soton but it is only GW4 and we've conceded in 3 out of 4 games.
I'm hoping now with Ronaldo and, as you say, Varane and Sancho bedding in we'll get a lot more consistency than last season. We bloody better had looking at those names and the calibre of player they are anyway!
The most worrying thing about Chelsea is how Tuchel has a clear system that he gets them to execute really well, even when they're having to make changes to the starting XI.
I think he currently has a record of 14 clean sheets in 23 games in the league. However, in three of those games goals where only conceded because:
Dippers this season - A peno, but where able to hold out a whole half with the kitchen sink being thrown at them.
Sheff Utd - Farcical own goal
WBA - Fell apart after going down to 10 men.
For me, they're the toughest team in the league to beat. Question is whether they will get enough goals to turn draws into wins.