I ask myself this now, not just because I posted about shark-jumping indirectly yesterday, but because I watched a two-hour Smallville episode that focused on an old super-group--the Justice Society of America. It was clunky as the linked review suggests, but it also moved away from the main plot of the year--Zod. The show has been going downhill for the past few years--especially after losing Lex Luthor, his father, and Martha Kent. Makes the show cheaper, but lost some of the more interesting folks who could spin good or bad plotlines in interesting ways. Last year's Doomsday was actually an ok plotline for the season, but this year's Zod? Well, all I want to do is kneel before him instead of watching this plot. I am nearly out the door.
So, what constitutes either a show-breaking shark jump or the point at which the downhill slide is either too far or irreversible (despite Jack's assertion that nothing is irreversible)?
- When characters do stuff that betrays the logic/past of their character. Like when truly bad guys start doing good deeds because of a convenient mind-swipe (Heroes).
- When the deus ex machina becomes so blunt that one can almost see the strings. Like a helicopter crashing on a guy who already lost his arm to a helicopter (ER)
- When a central character departs (Happy Days) or dies (John Ritter, Phil Hartman). Shows can survive secondary characters taking off or dying (Cheers, MASH), but the replacement has to be good and have good chemistry.
- When a younger child is added to the mix because the children in the cast have gotten older and less cute (Oliver in Brady Bunch). Indeed, if the obnoxiously new kid takes away from the formerly young but now quite attractive older kids (Marcia, Marcia, Marcia), this is doubly dangerous. The Cousin Oliver Syndrome even applies to animation--Scrappy Doo.
For more, see the wiki entry on Jumping the Shark, which includes this rule:
Another category, entitled simply Ted McGinley, usually includes any show that has featured McGinley in the cast. He has joined the casts of several popular shows after their zenith (The Love Boat, Happy Days, and Dynasty), earning him the titles of the "Patron Saint of Shark Jumping" and the "Grim Reaper of Television". Shows on which McGinley appeared from the start have, in most instances, been critically panned or canceled quickly. However, when he joined Married... with Children in 1991, the show stayed on for another six years.
Unfortunately, the handy website that contained a bunch of info about shark-jumping was sold to TV Guide and lost all of its content--jumping its own shark.