When faced with the choice of actual data and your beliefs, argue with the data.
Seriously, it's in PGs interest to have correct readings; otherwise, who would go and incur the costs?
Buy a radar gun (cover the cost by skipping one event); use it at local HS and college games. Play this game: gun without looking at the number and see how close you are. If it's so easy to get it right, why do scouts gun prospects until they get a base line (at which point they move down the line to watch more parts of the delivery)?
I've been using the radar gun for over a decade, gunned literally thousands of pitchers and I can get my eyeballs (usually) within 2-3 mph of the guns reading - up or down. BUT, I still use it because I want and need accuracy.