I think reffing has gotten better over the years. It's not perfect, but it isn't in any sport. But it seems like in years past there was at least one egregious error per card. Now they are fewer and farther between.
Big John has had a resurgence imo. I think he's handled himself pretty well. I do remember thinking he didn't do great when he reffed Bellator kickboxing, but it was likely pretty new to him.