...Sounds like someone used to work in upper radio management... That's the "everyone's disposable" attitude that has never done and continues to not do radio or related industries any favors.
I've always thought the traffic reports on WBZ have unique styles and quirks that make them enjoyable to listen to in different ways. Not saying they're must-listen radio for all, but any casual listener who tunes in the same time frame every day, day after day, year after year wouldn't notice they're suddenly not listening to the same person. Then there are the regulars listeners who absolutely would know.
I recently saw a "News Center 5 Eye Opener" promo where Kevin was the fill-in traffic anchor for many years. There was someone else there instead. I have no personal knowledge, but would assume a health or other personal issue may have made him step away for awhile, or maybe he simply chose to quietly retire? Dec/Jan isn't an unheard of time for that.