Before we get to the catcher in a steal situation there are a number of things out the catchers control
01-- how well the pitcher holds the runner on at first
02-- how quick the pitcher is to the plate
03-- what pitch is thrown---is it off speed?
04-- location of the pitch when caught by the catcher
Basically all of the above have to be near perfect so a catcher can throw out the runner
A 1.8 pop time won't mean beans if the runner gets a great jump, the pitcher is slow to the plate and the pitch is in a bad location ie--down and inside
Throwing out a runner is a "team" effort between the pitcher , catcher and infielder taking the throw