There is probably more to the story than just that the promo pack got someone's attention. Most likely, a booking agent made an initial call, got some positive feedback, and followed up by sending the promo packet--The promo packet simply verified everything that the agent said on the phone--

That is a bit hedgy, I know--as a one-time concert/music festival planner, I can tell you what I needed to to hear from a booking agent: That an artist had the right kind of show for my audience, that the performer(s) was good, both as a musician and as an entertainer, and that I could count on them to deliver a good show--

A good promo package backs that up, with clippings, a tape or CD, a promotional piece that clearly tdescribes the show, and a backgrounder, press release, and publicity photos for my promotional needs(fliers, ads, PR)--

Sadly enough, smallpiper, organizers, planners, and program directors do everything on the run--they don't have time to do a lot of listening, research, or auditioning--A friend that booked concerts for a campus radio station once told me, "I don't even have time to throw out the unsolicited CD's that I get--I have a group volunteers who do that--"