My best guess is based upon overall distance and proximity. I know that a short green pitch has a better chance to be within 1' while a 200+ Yard approach is granted a wider circle of closeness, I recall something to do with 5'. The WGT News page does not offer any links either to explain more details what the Reward requires to qualify. My assumption is that a posted score to the CTTH Leaderboard; however, only the top 70 are shown, while Sweeps are a Random draw entry.