Looking at the rough Radio-Locator maps, I'd say the contours of both stations match my experience during my many years of driving on I-91 and Routes 5 and 15 between Hartford and New Haven. On 94.7, WMAS was gone completely before I got through Wallingford, while WHYN-FM hung in there on 93.1 until running into the signal-conflict mishmash Joe Louis reported, around the North Haven-Hamden line. The WJMJ translator dominated 93.1 for a very short stretch of road (between Exits 12 and 10 on I-91) but by the time I reached New Haven, WHYN-FM, now scratchy, was the only readable signal.
Joe and other North Haven listeners will always have a tough time on those frequencies, but as SomeRadioGuy posted, none of the full-power stations involved have North Haven within their primary contours, nor do they program for (that is, sell advertising based on having an audience in) North Haven. Furthermore, the plain vanilla AC formats of WHYN-FM and WMAS are duplicated or even triplicated on the radio dial in that area with stations from the Hartford and New Haven markets. Unless Joe has a past association with the Springfield area or knows people who work at those stations, there's no obvious reason he would even want to listen to them when he can hear the same songs on WRCH, WTIC-FM, WEZN or WEBE. That makes him more a DXer than a targeted listener and, as such, his ability to pick up WMAS or WHYN-FM is a purely personal annoyance rather than an issue for the stations or the FCC to be concerned with.