Havlicek
These people are called the "announcer"
crier
The announcer
A herald.
When Babe Ruth the ball out of the park the announcer screamed "Holy Mackerel!"
They were called heralds.
A Nascar annoucer is called a commentator.
Ringmaster, ringleader or Equestrian Director
It is called a "ball"
A half ball is called a hemisphere.
When a ball has scored its last hoop point, it becomes a rover.