When I did it, it wasn't very difficult. Maybe about a third of the professors I talked to agreed to talk to their admissions department on my behalf, which is remarkably high considering that I had not received any official recognition for my work, I had some difficulty explaining it coherently, it was really only slightly impressive, and I'm a bit short on social skills, which are useful for impressing people (I had a lot of really awkward meetings with professors). Andraka at the very least has a huge advantage over me in the first and third of those problems, which should give him a sizable majority. If he's solid in the second and forth problems as well, I would expect him to get an overwhelming majority.