Sorry for the length,
@The Zetterberg Era - I don't disagree with your assessment, but I very much get the impression that this is more than just a 'hard-nosed' player taking someone to task and where exactly that falls in this. Your point of VAN is a mess, and that having the face of your team as a 25yo Hughes, and a big of a revolving door of coaches to try to wrangle manage the interpersonnel relationship of Miller and Peterson is a recipe for disaster. It's a fairly large organizational failure of the front office, ownership, etc. that this wasn't managed for effectively and to allow it have go as far as it has. Relationships, management, and leadership are learned skills just like anything else and I would argue that one of the things that JT Miller has proven time and time again, is his inability to be 'a leader'.
But VAN being a mess and being responsible for this situation, doesn't make JT Miller not a key contributor to the situation.
I think he's tough, and works hard, and has had unbelievable success on the ice because of those things. But despite being as talented as he is - he's now on his fourth team in less than 8yrs. His leadership style might be effective in some capacity, but the hallmark of a good teammate, a good leader, is being able to bring out the best in those you are expected to lead and knowing when to push, when to support, when to critique, etc. The fact he has effectively worn out his welcome in so many locker rooms despite the fact he's such a premier player on the ice, tells me he's a pretty intense and difficult person and probably worse, is he shows either no self awareness of this or personal accountability that he might be the issue otherwise he might have tried a different approach.
The result is still the same that he tries to intensely force a player into performing which is was obviously not working; a wiser more effective leader should try different approaches or reach the conclusion that the individual is inherently flawed (given that the Petterson has performed in the past and has proven capable, that shouldn't be the issue here). I suspect when Miller didn't get what he wanted, he doubled down even harder. I think Miller is a badass, old school player, but I do not think he's a leader nor would I want a player like him in a locker room that didn't have a Sidney Crosby-level of credibility that was willing to keep him in check. Quite frankly, he sounds like a really passionate guy who wants to win and is a huge d*ck to anyone who can't match his intensity - which is going to be most people.
Your Yzerman/Feds example is a good one. I would expect that you dropped 31yo Miller into the Wings locker room in 98, he would've absolutely hated 28yo Fedorov and rode him mercilessly. But that wasn't Fedorov, that wasn't what motivated him. Fedorov was a bit...mercurial. He never had any ambitions to be 'the guy' in the sense of the responsibility of being the leader of the room. He was, to this day, probably the more physically talented player I have ever seen play. There was literally nothing he couldn't do when he wanted to do it and often times because he has so many gifts, it looked like he didn't care or was floating for large parts of games. He could have had 100pt seasons over and over again, Selke Trophies, hell... when he played D for the quarter of the year, he could've contended for a Norris if he made that his full time position. He was often aloof in interviews, he seemed like he cared more about dating celebrities and driving his Porsche, etc. EP isn't quite all of that but in terms of his approach and his talent, I can see why its frustrating to a guy like Miller.
The difference between Yzerman and Miller is, yes, Yzerman was intense, yes, but he also encouraged and supported his teammates. He knew what made Feds go and they would talk regularly (I know this as I would talk to Fedorov on occasion). They always had good conversations and he would encourage him - but Stevie was private in that way when dealing with these things because he was able to flex his leadership style for Fedorov (with the help of Larionov as well). The point of this is simply: just because Petterson isn't working out in the VAN situation with Miller putting him on blast in the room, etc. and him not responding to it - doesn't mean he wouldn't find the support or a better situation with the Wings. The Wings do not have anyone like Miller and in fact, I think Yzerman has gone to great lengths to purposefully eliminate certain personalities in that room and encourage others ( a good portion of my support of Copp) who are good guys who want to help the others in the room.
I do think much of EP's performance currently is due to the utter show that VAN is and a pretty bad shot to his confidence. We know he is a capable ppg 1C with incredibly high defense, do we think he can find that form with the Wings? Maybe. I think our locker room is actually pretty good with a good group of guys who get along and support one another. I also don't think Yzerman would ever allow any disputes or friction in that room to persist and he would nip it in the bud quickly.
Just my 2 cents