Okay, maybe it's not just some random guy on the Internet...
It's some random guy over at Beyond the Box Score who says: Edinson Volquez' [sic] ERA Cannot Last.
In short, he regresses ERA on baserunners/9 innings, using 1,000 datapoints since 1999. He finds an R-squared of 0.66, and concludes that predicted ERA from this regression is destiny. Hence, Volquez's ERA will rise, while Cueto's will fall.
As I commented there, it sure is a good thing that correlation=causality.
However, this does provide some evidence that Volquez and Carmona (as I was wondering earlier) have either been quite lucky or are doing something very right that we don't understand, while the opposite is true of Cueto. My main problem is jumping beyond that knowledge to pronounce the end of the reign of a low Volquez ERA. Sure, it's likely to rise, but I'm not particularly buying this argument.