I have to find a quote about his wet driving but I read he is driving too agressive in wet and he loses more time on snaps and mistakes then he gains by driving more aggressive. For example neither Max nor Hamilton drive aggressive in wet, they are more calculated and searching for good lines instead of being on the nose aggressive.
In the end though that's on Charles. Max and Lewis adapt better and, more importantly, adapt instantly to such conditions. It just doesn't seem that Charles has the same feel on a full wet track. In the two wet qualy sessions last year Seb smacked him. That's the reality.
Still it isn't a massive deal. If Leclerc can be brilliant in most areas and that's his only weakness, you'll take that. Imo wet weather ability is slightly overrated in the big picture. Senna at Portugal 1985/Donington 1993, Schumacher at Barcelona 1996 etc is all spectacular and sexy... but they didn't dominate every single wet/mixed conditions race they ever contested. Performance in such circumstances does tend to rely on set-up and other factors almost as much.
There have been plenty of drivers in history who I thought wouldn't be any good in the wet... yet they won wet races (and dominated some). While there has been drivers I thought would be spectacular in the wet (big balls, great car control, very brave in the dry...) but actually weren't.
It's a strange sport sometimes.