They move product.

IMO, getting an amateur staffer deal is more about your personality than performance. The manufactures are looking for guys who are charismatic that can push their brand well.

Another option is entering tournaments or joining leagues that award staffer contracts to top bowlers, then prove your worth as a company personality to get additional contracts

Like your honesty,Gid

Staff positions break down unofficially in the following ways-

Nationally recognizable bowlers
Pro shop owner or operators
Local influential bowlers, there really aren't many of these, but there are a few
The guys the sales rep wants to have beer with when he's in the area

If you don't have a pro shop or are a recognizable name it is like everything else in the world, who you know.

They are not coaches.  They are locally known bowlers who are pretty good.  Some of them do ball demos so that is a way of pushing their product.