There's a lot of negligent, criminal management stories, but if we are talking star players -
I think Dean Lombardi is a colossal piece of shit. When he was rumored to be in the running for a Canucks' executive position, I was so pissed and worried he'd end up with this team, and I think the stars he didn't. For why I think he's a colossal piece of shit, I need to give some background to the Slava Voynov situation. Voynov was a defensemen the Kings held in high esteem, except he was then accused of assaulting his wife in a horrific case of domestic violence, where many of the details were readily available to read. It was horrid. Voynov ultimately plead no contest to a charge of corporal injury to a spouse, was suspended for a year by the NHL, and never played in the league again.
However, during this suspension, this didn't stop Lombardi and his LA Kings from trying to sneak him into their practice facilities to continue skating and being with the team. He was a full participant in practice until the league got wind of it, and the league fined the Kings $100,000.00. (chump change in the grand scheme of things, but at least sticking to the guns of their suspension).
As for how this relates to a star player, let's compare Lombardi's reaction and treatment of a man who plead no contest to beating his wife, to his treatment of Mike Richards. Mike Richards was arrested at the Canadian border for being in possession of Oxycodone without a prescription on June 17th. In this case, Dean Lombardi reacted swiftly, terminating Mike Richards' contract on June 29th - just 12 days later. There was no sneaking Richards into practice facilities, and no attempts to work with the player at all. Why? Because Richards was on a bad contract. His play had deteriorated and Lombardi, scumbag that he is, pounced on the opportunity to terminate it and then went public with a bunch of crocodile tears talking about how he was "played" by Mike Richards, and that what had become of him was a "tragedy".
But the tragedy he refers to isn't even one of a person who may or may not have been dealing with substance abuse issues, but rather talking about his decline in play. He then went on to say that Richards should be held accountable for his actions, and that he was in a destructive spiral. A far cry from his actions on Voynov.
And the kicker, to me, is that Richards' charges were stayed by the courts in Manitoba. He returned to the NHL with the Washington Capitals the following season.
TL; DR - Dean Lombardi was just fine with retaining a wife beating asshole and sneaking him into practice facilities because he was a young player on a good contract. On the flip side, when a respected veteran got caught up in trouble, he waited a matter of days before kicking him to the curb, publicly eviscerating him, and crying the victim.
f*** that guy.