I think they picked Simpson because they feel he is best case scenario if Stafford goes gets injured and has to miss some games.
Thats based on not having to spend a large amount of cap money on a veteran free agent. I think Simpson can replace Carapollo and match his value.
Rams picked up a lot of players that could provide value next year or next year or two which good coaching and learning the Rams system.
Simpson cam pass the ball, read the defense and go through the progressions already and had McVay and Stafford to learn from.
I like a lot of the players the Rams picked.
Not all draft picks make it in the NFL but many they took look promising.