Anyone know the formula WIS uses for a catchers caught stealing percentage pre 1960?
Examples:
Elston Howard 1958
Actual: .48 WIS: .36
Elston Howard 1959
Actual: .64 WIS: ..34
Elston Howard 1960
Actual: .51 WIS: .51

John Roseboro 1958
Actual: .37 WIS: .27
John Roseboro 1959
Actual: .60 WIS: .45
John Roseboro 1960
Actual: .45 WIS: .45

The CS% numbers start to match starting in 1960. Why were the catchers pre 1960 being changed?

https://www.whatifsports.com/devchat/devchat.asp?chatid=51#4238

as of this chat, all CS data from before 1960 was made with a model due to incomplete data pre-1960.