Nobody really knows. If you look at the ROFR threads, you'll see cheap contracts make it through that surprise all, expensive contracts get taken that make no sense.
Understanding there is a waitlist for VGC and BLT of substance, not very many contracts get taken even there. Now, you have to match the waitlist use year and # of points, but still.
It appears to be very loosely tied to price and demand - but not clearly.