Muckler inherited a great YOUNG team that existed in an era where players were cost controlled until they hit UFA, and the UFA age was 31. He didn't DO anything to "keep them great". He was given a ton of young elite players, and a farm system that wad the envy of the entire league, and all he had to do was put his feet up and enjoy the gift he was given.
Murray inherited an aging good team whose cup window was very quickly closing, and with no assets left in the organization to cope.
If you think the team Murray inherited was in any way set up to succeed over a long period of time in the way that the team Muckler inherited was, then there's nothing left to discuss, as we clearly aren't even having the same conversation.
I'd argue there were three perceived issues with the Sens:
1. Jaques Martin, while great in the reg season, was consistently outcoached in the playoffs.
2. Goaltending was well below the standard set by the rest of the team, all apologies to Lalime who was a great guy.
3. Team toughness was seen as an issue.
He addressed point 1 by bringing in Murray, who as a coach was certainly a success, the who's to say how Martin would have done in the same situation.
He tried to address point 2 by bringing in Hasek. This turned out to be a failure, and continued to be one with the acquisition of Gerber.
I guess you could argue he addressed point 3 with McGratten, though I'd argue Marshall Johnston had already done so with Chara and Neil. Please don't try and tell me swapping Hossa for Heatley changed team toughness in any way. Good 'ol Canadian kid vs heartless European tropes don't really carry much water here imo.
So in terms of addressing perceived issues, he took action, was successful in one, unsuccessful in one, and at best a wash in the third. This of course is before evaluating whether or not the perceived issues were true issues in need of being addressed, which is a little more hypothetical in nature.
When Murray took over, he needed to address the crumbling farm system, which he surely did, the goaltending, which he eventually did, fill a coaching vacancy which his promotion created, which he failed hard at. In the latter half of his tenure, additional constraints were added in terms of finances.