(Sorry if this has been mentioned already)
Lombardi also talked about Young on Bill Simmons podcast and pretty much called him lazy/unprepared for most games.
EDIT: These comments were made last week but it might back up Fisher's decision a little.
Yeah, I have heard these comments. However, even though I feel like I support Young a little too much in the Fisher/Young argument, I got to say that I feel his unpreparedness for games comes from the Fisher/Collins relationship. (By no means do I hate Kerry Collins; guy's one of the best back-up quarterbacks in the league right now and he's a Penn State grad.) In 2009, before the season started, there were reports that Vince went into Fisher's office and demanded his starting job back. Fisher obviously refused and didn't make it a competition in the pre-season, then watched as the Collins-led Titans started the season 0-6. (By the way, what "great" coach starts a season 0-6 and gets a 59-0 asswhooping after returning most of his 13-3 team a year ago?)
Bud Adams had to get Fisher to switch quarterbacks. (You could make the argument that Bud is the reason for all of this, considering he's a Texas guy and wanted Young in the draft, while Fisher wanted Cutler, and Norm Chow wanted Leinart.) Now with the entire team back on his side, Young led them to a 8-2 finish, barely missing the playoffs. This season he came in as the clear-cut starter, then had a nice first game against the Raiders.
The Steelers game is where this mess that we have now began. Young didn't practice during one or two of the days because he was at a McNair lunch/breakfast, something that was related to McNair. Obviously it's been documented that those two had a close relationship and it really hurt him when he was murdered, so he's going to go out of his way to help that family out for the rest of his life. Anyways, he gets benched mid-game after throwing two picks and losing a fumble. Collins comes in and does almost the same thing, then puts up stats against a prevent before the game finally ends.
Young's attitude has always been a problem, I'm not denying that whatsoever. With him though, there's that lack of trust between him and Fisher, which has stemmed from multiple things. It looked like they were fine until that Pittsburgh game, then Young started (at least IMO) to worry about Collins supplanting him as the starter. I think Fisher's bias towards Collins may be a reason why he's been deemed "unreliable" by unknown sources.
Young probably needs a change of scenery, and like I said, I'll support him if he does go somewhere else. But this is the third time Fisher has mishandled his starting quarterback (although the McNair case was more on the front office), and couple that with the barely over .500 record, 5-6 playoff record and nothing to show for a 17 year stretch besides an AFC Championship...I think if anything, both of them need to go and we need a fresh start in Nashville.