Part of the Marlins complaint was likely that, regardless of intent, for two straight pitches Fiers had not demonstrated the ability to pitch inside without putting the ball near someone's head. If you can't do that, then quit pitching inside. You can argue, the day after as a fan, that that's not fair, but it's completely understandable why someone might feel that way. (A few years back a Cubs pitcher hit like 4 batters in the first few innings vs Pittsburg, I think, and they were pissed, even though it was obviously unintentional.) And Fiers' reaction was gasoline on the fire.