I think that Martin flirted with jumping the shark (although it's commonly accepted that the show officially jumped the shark when Tisha Campbell accused Martin Lawrence of sexually harassing her during the last season) the first time when WZUP got sold (and turned into a country music station) and Martin subsequently lost his radio job. Stan's stinginess and overall sleazy vibe and Shawn's affably quirky demeanor brought another dimension to the comedy. When they were written out, Martin didn't have a whole lot of other people to play off of and explore his current issues with. This was around the time I think that the writing started to become more formulaic.

I was very surprised when the radion staion was sold. I guess the production was trying to give the show a new look and take things in a different direction.