Jeff, it's my understanding that Arbitron combines the ratings for all simulcast stations in the market into one line.
http://www.radio-info.com/markets/buffalo-niagara-falls
I don't think the people on the Buffalo board are correct in claiming WBEN-FM (the former WLKK) got a zero. It looks that way at first glance, but really, it's because WLKK-FM no longer exists. Now that it's WBEN-FM, simulcasting WBEN(AM), the combined total for both stations is all credited to WBEN(AM).
After all, if Arbitron has diary entries that list program names, or just call letters without an AM/FM distinction, they've got better things to do with their time than try to "ARBITRarily" (sorry, it's late, I'm tired, couldn't resist) decide whether to credit the AM side or the FM side.
Usually there's a notation indicating call letter changes and simulcasts, but I'm guessing either radio-info.com missed it, or maybe Arbitron doesn't bother with it for the trends, opting instead to wait until the next "full book" report.
Bottom line though, the latest result for WBEN-AM shows an increase from 7.2 to 8.5 trend-to-trend. So at second glance, it appears the FM simulcast helped WBEN, but the Entercom cluster, as a whole, didn't gain much. Then again, for the sales staff, that 1.3-rating from the FM side is probably more valuable as an addition to WBEN's existing audience, than it is on its own as a separate format.