Right once these letter grades were announced, I was VERY confused as to what factors would play into these. Looking at these grades, though, it's clear that price and popularity play a pretty insignificant role. I just revised my post (for legal-ish reasons), and LTC, Dash, and several others were the ones that REALLY surprised me.
Because things like ETH and EOS received the highest grades, it's clear that technological aspects play a much larger role in the determination of these letter grades. So, it seems like LTC and Dash should have received a higher grade than BTC (again, just based on the factors it looks like they were using).