Tbf to Brandon the fact he ever even made the NHL is good going. Not that talented and at lower levels known as much for fighting as playing hockey.
I mean, I don't like his game, and think he is a ~#7 NHL defenseman. But the talent he has has almost certainly been made the most - or close to the most - of.
Sorry, I was being a little tongue in check.
Manning got sorta stuck between AHL roles, where he was actually a solid offensive defenseman, and his talent limitations at the NHL level, where he often gets caught doing too much without the recovery speed to cover his mistakes.
I think he could be a solid #6 D-man if he played more conservatively and cut down on the bad pinches and getting caught deep in the O-zone. I think he was a victim of a thin organization, where he was asked to do too much at the AHL level - and this may be why they let Brennan play the offensive role, and have the young defensemen focus on defense so they develop better fundamentals - does it matter if Brennan knows how to play responsible defense? Whereas if Myers dominates offensively but doesn't improve his defensive positioning he's not going to be NHL ready.
