The point is, we just don’t know. Stupidly simplistic numbers such as percentage of shots faced yield no useful information. A shot on target can be from any direction, at any angle, at any speed and from any distance. The figures I’ve seen have a surprisingly tight spread, something from 60% to 70% which means that there is not a lot to choose between any of them.
As random number generators go goalkeeping statistics are as good as they come.