Fuller, Williams and Joseph day are all good players. You’re underselling their talent by bit.
Joseph-Day is a good player, and I will give you that and he is probably better than A-Shawn Robinson.
Jordan Fuller? Really? 2nd season. 16 starts. Giving up over an 80% comp rate and 99 pass rating for his career. Good?
Darious Williams is similar. 4th season. 16 starts. Very unproven but he has shown he can make picks but that happens when you have Donald.
Here is the thing about the Rams. The sum is greater than it's parts outside of Donald and Ramsey. They play a safe, shell coverage to allow players to have their eyes on the QB and make plays when QBs are rushed. Donald plays 90% of snaps which is unheard of and the Rams essentially count on creating a negative play to stop teams in positions to have to throw. They move Ramsey and Donald around to take-advantage-of and create one-on-one matchups. This is why they can plug average players in and have success. They do everything that Vance doesn't.