[Written by the writer of that very episode][link]. More than a little defensive, but it is somewhat interesting to hear the guy talk about it like this.
He seems to be confused on one point, though.
Jumping the shark doesn’t mean a decline in popularity, though. It means a decline in the qualities that made the show good to begin with. Jumping the shark is the point at which the show you liked starts becoming something else; generally something worse, at least from your perspective as a longtime fan.
[link]: http://www.latimes.com/entertainment/news/la-et-jump-the-shark-20100903,0,6800871.story “First Person: In defense of the ‘Happy Days’ ‘ ‘Jump the Shark’ episode – latimes.com”