The only real takeaway from that article is that he gets a lot of IFFBs (typical of extreme FB pitchers) and manages LD well.
The rest of the article is stupid. Using a pitcher's OBP and SLG to create an ERA estimator, and then using its proximity to his ERA to argue that his ERA is closer than his FIP to his true talent is lunacy. The ERA was low because the OBP and SLG were low. To question whether the ERA is a skill is to question whether the OBP/SLG was a skill.
All that to say, he might induce weak contact. He probably does. But that's not going to turn a 4.9 xFIP into a sub-4 ERA over the long term. No pitcher in history has been that good at managing contact. If you're projecting Estrada at a sub-4 ERA, you're banking on a K/BB skill improvement, a GB skill improvement, or a combination of the two.