At Hop School they said Agronomics comes first. Disease resistance, yield per acre, ease of processing, time of maturity, and so on. One plant was pointed out that had a huge crown at the top, Jason Perrault said that was a failure as it would jam their machinery. When they get to a certain point in development, they brew beer with them on a homebrew set up. It looked like many use a 20 gallon More Beer system.
There seems to be some luck, but the pros like Jason Perrault have a good feel for what increases their chances.