Unless you can look at the gill rakers, we are all speculating which is definitely fun to do!
If I had to make a SWAG, I'd guess it is a pure BG with some unusual genetic variations. However, if the BG was from a stream fed pond, or a pond I knew had a population of LES or RBS, then I might say it was a BGxRBSxBG or a BGxLESxBG hybrid. As in it's 75% BG and 25% the other parental species. Hybrids are just so hard to ID when you don't know what and if there are other species of sunfish around.