Until one actually hits with an ex pro, or current pro, they have no effen idea what they are talking about, and absolutely no point of reference. This thread is an example of those who haven't.
A pro would absolutely demolish a 4.5 player.
There are high school kids right now that play baseball, and throw over 100 mph, and they would get absolutely tattoed pitching against a bench player in major league baseball. Why?? Because they haven't learned how to actually "pitch".
This is so true it hurts. It's one thing to have the raw physical ability to hit the numbers (100 mph pitch, 120 mph serve, etc). It's another to do what the pros do, which involves not only physical talents but deep training that goes beyond what any of us will know.