This switch definitely wasn't as noteworthy of a format change for rock in Boston as WBCN, WFNX, or WAAF, but still another loss for Boston. WBOS, in its 35 years as some sort of rock format, has almost always underperformed, especially after 2008 when they adjusted from AAA to alternative as "Radio 92.9."
It arguably underperformed as a country station, too, though it had better numbers as "New England's Country" than it did most of its time doing some derivative of rock. Seemed like WBOS abandoned country right as it was taking off, and I never understood why it didn't quickly flip back when the format was hot. Boston was without a country station for almost three years, and the station that flipped to country (WVBF 105.7) was doing better than WBOS. I've never bought the notion that some stations are just cursed, but 92.9 would be a good case against my argument.