I don’t know what Chelsea is doing with so many goalkeepers when they can only make use of one in a match. I don’t really think goalkeepers should be what Chelsea will be fighting for right now, there are other positions where Chelsea is performing poorly that they need to fix. Chelsea's defense is just too poor, it was just too easy for their opponents to penetrate during the preseason matches. I think they need to fix that, because no matter how good a goalkeeper is, if the defense is poor, then people will think the goalkeeper’s performance is poor. When Chelsea are singing, they should focus on quality players and not just signing random players.
Since after that Peter Cech was sold, and he retired, Chelsea hasn't gotten a perfect replacement for him, Thibaut Courtois and Mendy would have been two different keepers to have taken the position of our their unforgettable legendary and Champions League winner peter Cech but Thibaut Courtois left Chelsea for Madrid whereas Mendy couldn't leave up to expectations after a couple of seasons with Chelsea, So I kind of believe that Chelsea is making all necessary efforts to buy a keeper replacement for Peter Cech, whom will not only just keep for few seasons and leave or lose form but a keeper that will have a memorable place in the club's history.
It could take a while before Chelsea would get a keeper as good as Peter Cech. So far, he's still the best they've ever had but if Chelsea take their time to scout upcoming stars sign one that comes close and work on him, then it would be better for them, the best thing Chelsea did to Real Madrid was giving them Courtois he's a good keeper and would've come close to what Cech did at Chelsea if he was still in the club, well I might be wrong though cause the general team performance matters too and if their defense wasn't good enough to back up Courtois then he'll be exposed to goals no matter how good he is, just like it happened to Man United last season. However their a some keepers that would still deliver, with or without a good defence, let's take David De Gea for example and those are the quality a top Club like Chelsea needs, not signing numerous options that would end up being a liability to the club.