Greinke is such a boss, should start the ASG.
But ERA is a stupid stat, holding the other team scoreless is overrated.
I don't think that anyone is actually ever arguing that having a low ERA is anything but good. The issue with it is simply that it does not give you a complete story. A pitcher that is allowing a number of baserunners but didn't give up the corresponding runs is almost certainly just lucky. Getting out of a jam is more luck than skill, because clearly the pitcher is doing something to get into those situations, and more often than not, they'll continue to do those same things over the course of a season. The only real question for me is what weight you want to put on that kind of luck for evaluating past performance. For projecting future success, it's absolutely vital, but I can at least see an argument for rewarding a pitcher with an ERA that is not indicative of his real ability.