Well, I've come to the conclusion that he's overrated as a coach because he's got an owner who's never fired him. Look at his long-term record over those sixteen seasons - it's good, but it's not great. Something like .550, maybe not even that. A lot of 8-8 seasons in the mix. Almost had that one Super Bowl, but that's really it. Seems like he's had more than his fair share of issues with his team and his players over the years, guys like Haynesworth aren't all on the coach but he's not absolved from any responsibility (and Haynesworth wasn't the only one).
And, his team has quit on him multiple times in recent seasons. Two years ago, when the Pats beat them 59-0, the Titans just quit. There were times this season when they weren't giving it their all.
Now, he's not a BAD coach, but I'm not sure that every owner in the league would have stuck by him for those 16 seasons. He'll probably do well wherever he lands... but he's not a savior.
EDIT: His record.
Team Year Regular Season Post Season
Won Lost Ties Win % Finish Won Lost Win % Result
HOU 1994 1 5 0 .167 4th in AFC Central - - - -
HOU 1995 7 9 0 .438 3rd in AFC Central - - - -
HOU 1996 8 8 0 .500 4th in AFC Central - - - -
TEN 1997 8 8 0 .500 3rd in AFC Central - - - -
TEN 1998 8 8 0 .500 2nd in AFC Central - - - -
TEN 1999 13 3 0 .813 2nd in AFC Central 3 1 .750 Lost to St. Louis Rams in Super Bowl XXXIV.
TEN 2000 13 3 0 .813 1st in AFC Central 0 1 .000 Lost to Baltimore Ravens in AFC Divisional Game.
TEN 2001 7 9 0 .438 4th in AFC Central - - - -
TEN 2002 11 5 0 .688 1st in AFC South 1 1 .500 Lost to Oakland Raiders in AFC Championship Game.
TEN 2003 12 4 0 .750 2nd in AFC South 1 1 .500 Lost to New England Patriots in AFC Divisional Game.
TEN 2004 5 11 0 .313 3rd in AFC South - - - -
TEN 2005 4 12 0 .250 3rd in AFC South - - - -
TEN 2006 8 8 0 .500 2nd in AFC South - - - -
TEN 2007 10 6 0 .625 3rd in AFC South 0 1 .000 Lost to San Diego Chargers in AFC Wild-Card Game.
TEN 2008 13 3 0 .813 1st in AFC South 0 1 .000 Lost to Baltimore Ravens in AFC Divisional Game.
TEN 2009 8 8 0 .500 3rd in AFC South - - - -
TEN 2010 6 10 0 .375 4th in AFC South - - - -
Total[5] 142 120 0 .542 5 6 .455
Six seasons of ten or more wins, our of sixteen. One SB trip, another trip to the AFC Championship game. Meh. Seven seasons where they won 7 - 9 games (basically, .500 seasons).