If you can't understand it, it's just because you don't understand modern player evaluation
The formula Milner has used to be one of the most effective lefty specialists in the league the last two years has been to throw a bunch of strikes, get a bunch of weak contact, and strike out just enough guys to limit traffic. That looks like this:
23.5 K%, 5.3 BB%, 49.9 GB%, 85.9 Avg EV, 4.7 Barrel%
And then here's what he's done this year:
23.8 K%, 6.2 BB%, 51.3 GB%, 87.6 Avg EV, 2.5 Barrel%
Nobody can honestly say they'd be willing to bet with confidence which of those had the 2.79 ERA and which has the 5.03 ERA
He made a bad pitch to Hilliard and probably deserved that result, but it's not hard to see why he keeps getting chances. He hasn't actually been that different from the guy that was really good for the Brewers the last two years