I don't think it's fair to compare the teams of the past to the current Lions team.
In 2008 we went winless.
In 2009 we had very minor improvements
In 2010 we won the final four games of the season and came out an (almost) respectable 6-10
In 2011 we went 10-6 and made the playoffs.
Each year that Mayhew has been in charge, we've seen improvement. Until 2012 when injuries did pile up, the receiving corps was decimated, our feature running back was out the entire season, and the defense cracked but didn't break.
Going into 2013 we have a featured running back in Bush. We have an improved secondary with Glover Quin. We have a solid draft position. We still have the money to fill holes.
I think the 2013 version of the Lions looks like a more talented version of the 2011 team. More experience at key positions (like Fairley), more talent at position of need (Safety), and we should be right back on the right track.
Past Lions teams never showed consistant improvement. They were all over the map. Great one game, horrible the next, and season by season it was just an overall sense of "suck".
Mayhew's Lions have shown improvement every year but one... and that was a year racked with injuries. Let's not be too quick to throw the baby out with the bath water. Mayhew has earned a little faith from the fan base.