He is definitely getting lucky on balls in play, virtually every metric that tries to account for the quality of contact given up or context/sequence neutrality thinks that his ERA should be a run or two higher than it is. He has given up a very small number of HRs relative to how many fly balls and hard hits he has allowed, and nothing in his career numbers suggests that his HR/FB rate shouldn't rise substantially moving forward. If he keeps walking people at this rate, the runs will pile up quickly once balls start leaving the yard on him again.
Still been a good return, and nothing can take back the wins that he has already gotten, even if they are heavily luck-influenced, but it doesn't seem like much has changed for him this year, other than throwing his slider a lot more, so it's probably safe to assume that his numbers will suffer a bit as his luck evens out. He didn't add velocity to his FB, he isn't getting more swinging strikes, he isn't throwing the ball in the zone more, or inducing significantly worse contact, etc..