First of all, this along with his disdain for walks are the major reasons why Diamond has been successful this season. When a pitcher gets a ton of groundballs, double plays are a major factor and damage is generally muted as any hit more than a single is rare. So he's able to put up some decent starts besides not being an incredibly impressive pitcher.
Even further on the extreme lies Samuel Deduno. The man who strikes out as many as he walks and yet post a league average ERA. I can't think of any other outlier this pronounced in baseball right now and am skeptical if this is even remotely sustainable. However, it is something to look out for and be cognizant of as you watch him pitch.