He was arguably the top HW in the league for years (along with Georges Laraque); compared to most fighters he was a much better player than most of them.
He always had a bit of a 'screw loose'.
Before he was traded there was a reported issue where he wasn't thrilled with his contract, and perhaps was 'holding back' on the ice.
I believe that came to a head when Scott Parker of the Av's couldn't get Brashear to fight, and becuse of that Parker ended up trying to take it out of Jovo. Jovo was way out of his league against Parker, so Bertuzzi had to jump out of the ice to save his buddy (resulting in a 10 game suspension).
Because of that, there were rumors of issues within the dressing room (Matt Cooke was rumored to have called Brashear out for it in the dressing room).
Around that same time, Brashear was in legal trouble for having assaulted a man that has asked his wife and child to leave the fitness area at their shared Yaletown condo.
Shortly thereafter there was yet another incident where Brashear beat someone badly outside of a nightclub in NJ (or Philly). I'm not sure if that was in the off-season while he was still a Canuck, or after he'd already been traded.
Brashear, when he was a Flyer (during the lockout) chose to play in the LNAH in Quebec. That league is full of crazies, and fighting is how it makes money. Brashear beat the tar out of a player trying to make a name for himself against the best. But, for some odd reason, that wasn't enough. Brashear then started slamming the kids head on the ice repeatedly ( i believe there were also some legal issues with that situation.
A lot of people hated the way he fought. He was incredibly strong. He'd bearhug his opponents and then use his strength to keep pulling them off balance and throw short little punches to their head.
Brashear also had a professional MMA fight during the lockout (i believe he TKO'ed his opponent quickly).
Once one of the most feared men in the NHL, Donald Brashear is trying to find peace after losing almost everything to drugs and alcohol.
theathletic.com