I disagree. I think if anything last year was an "On" year. If we want to talk about bad shows we can talk about 2008 and 2010. 2007, 2011, and 2012 were completely decent. 2006 was the only year that was REALLY funny to me. 2009 was really funny from what I remember, but I only saw the show once, I heard it plenty of times though.
2006 was the last year that was hilarious, and it's unfortunate that the show has been dictated by the state parody laws ever since. That is honestly my opinion, I'm sure plenty disagree with me, but that show was a lot better than Bill and Ted meet Hellboy and the producer guy from 2010. I'll take last years show over even 2011, which at times was only meta for the sake of being meta. Which is still better than the Family Guy esque jokes of 2008 and 2010, i.e. introducing a character to just make a joke about said character.
Bill and Ted is very subjective and can be very hit and miss. Since 2006 the one show I remember being absolutely hilarious was 2009, and as I said, I only saw the show once. Even really off years have really funny bits though. The bed intruder intro in 2010 was ridiculously fun and funny. The rest of the show might have been less than stellar for me but I died laughing there. 2008 had one of the all time funniest intros I can remember with Juno, Barack Obama and Daniel Plainview. Then you have 2007 which felt really stale at times but had some great one liners, i.e. MyBolognaHasA2nd name being Michael Myers AIM and the spot for Spiderman 3 coming out of Spiderman's ass. It's all subjective, but I've still yet to watch a Bill and Ted that wasn't at least partially funny to me, and some of them were really stale.