Trouba. And anybody who hurts his feelings by looking at him.
In all seriousness, I don't pretend to know what he goes through. He had to step away last season for mental health. His play is also much better when paired with Fox over Trouba, which everybody should have predicted. Expected goals % went from like 30% with Trouba to more than double with Fox.
I wouldn't say Miller makes one of the most mistakes through-out the entire league, but the issue is that when he makes a mistake you end up noticing it on the score board. A lot of players can get away with making mistakes because it's less noticeable than a 45 second scramble in your own end or a goal against. Give aways are a poorly tracked stat but for those that do care he's one of the lowest on the time. It's just that the giveaways, the pinching, and the brain fart moments lead to something that stands out when it's done.
Fans want him to be what he's not. A lot of us hoped he developed a mean streak. It's never happened and it never will. He's just not that type of player.