Dear god, they chose the two cheapest upstream providers on the market [1]. It's a shame they didn't pick up a higher quality carrier to handle the majority of their traffic.
Also to note Google Fiber uses a lot of nLayer/GTT for their eyeball traffic.
A close friend of mine spent years managing the network of a smaller ISP in the northeast using both Cogent/HE for their eyeball network, and he was constantly telling me about packet loss issues with Cogent. On the other hand, I haven't seen as many issues with HE as a whole, more localized.
Either way using the cheaper options is a good choice if you want to keep costs low during expansion. Hell, it's probably still better than what I see through TWC.
Want quality bandwidth? Pay for quality bandwidth. Most people just want their packets delivered, a few extra 10s of milliseconds be damned.