I don't think it has become a parody of itself, but I share y'alls grievances to the slightest extent. It's still my favorite sit-com on right now.
However, seasons 1 and 2 were all over the place and didn't have the greatest overall direction. Season 3's injection of Chris and Ben gave the show's star a direction to go and it rose through season 4 and into season 5. With the wedding things obviously get comfortable for the star and now it begins to lose a track again.
I think in this season you are seeing more season 1 and 2 but with comfortable actors across the stage. It tends to leave things stale at times, I agree.
However, if they can keep me laughing enough for 1.5 more seasons I'll be very happy with the series. I have loved it even when the show seemed lost at times.
That