Here is a great analysis of five comedians who used to be funny but are now tired but unretired. For instance, Chevy Chase is spared because he had the good grace to retire when he stopped being funny. These five did not. The analysis establishes when they were funny, why they're not funny now, when they jumped the shark, and what they can do to redeem themselves. This is good stuff. The only problem I have with the list is that the #1 choice, in my opinion, was NEVER funny.