NAC or "Smooth Jazz" developed in its broad national form out of the team that put together The Wave in LA to replace a declining album rock format. It was an evolutionary format, based on a lot of research by Frank Cody, Owen Leach and several Metromedia local programmers, a model evolved out of fine tuning and heavily researching the intents in the prior year to create the format in places like NYC, Orlando and San Francisco but which met with limited acceptance.
The Breeze was an adaptation of what Cox discovered when trying to do very traditional AC in Miami at WFEZ, basing it on the very old leaning sister station WDUV in Tampa. Realizing Miami was no longer a retirement community, they modified the format and introduced a subtle variant that now regularly ties with WLYF. But the origin of that concept was in Miami, and it is, again, a research based fine tuning of a format, not a new format.
This is a case of an obvious format for an audience that nearly no advertiser wants to buy. Companies as large as CBS TV have tried to get advertisers and agencies to buy 55+ to no avail. And this is not a new format... it is just a fine tuning of "oldies" with a more MOR presentation. It's hardly a new format.