It's amazing that he lasted that long on WEEI. His schtick was lame back when he was on NECN.
Yeah, I never understood how he had that job.
Hosting a radio show is much more difficult than most people realize. Try taping yourself talking for three hours, about anything, and then try to listen to it all the way through-- chances are it will be completely unlistenable, even if you are naturally a funny and insightful person. There is a whole art and science to speaking on-air, and especially to pacing and stretching out the good material, planning your segments, etc. It's not enough to be witty, you also have to be a good speaker and have a head for managing a show. Dealing with callers is a whole other thing.
That said, some baseline ability to be funny, insightful, and/or provocative ought to be a necessary, if not sufficient, requirement for hosting talk radio. If the art and science of broadcast host is about making one's personality appear to "work" in the unnatural context of a one-way everyday interaction with the public for several hours per day, then one ought to at least have those personality elements on which to build a show.
Mike Adams is good in terms of the broadcast stuff: his voice, his speaking, his ability to manage the flow of a conversation,etc. As a game show host or news announcer, or possibly even as a roundtable moderator, he could work just fine. But his personality, his perspective, his sense of humor are all on the spectrum from bland to bad.