This is generally a pretty good analysis but unless you're already defining the Berkshires to include the (more northerly of the) Hill Towns, the Pioneer Valley, and much (though not all) of the North Quabbin region--areas which are really not actually in the Berkshires--you need to concede significantly more of Western Massachusetts than you are. Republicans aren't going to be winning General Court seats from Hampshire or Franklin Counties for a long, long time, and by the time you get down to local offices party affiliation isn't that important anyway except insofar as local government can present eventual candidates for the General Court or higher offices. Hampden County is another matter. Springfield and Holyoke themselves are right out, obviously, but pretty much every other municipality in the county can be carried by statewide Republicans when the stars are right, and Brown 2010 and Gomez 2013 both I believe carried Hampden as a whole.
If I were a Massachusetts Republican Party operative trying to build up an apparatus that could be more consistently competitive statewide I would try to focus on the General Court, not in the interests of getting a majority or even doing away with the Democratic supermajority but just for the sake of narrowing the supermajority and fostering a deeper bench of potential statewide executive candidates with actual experience in elected office. There are quite a few House districts and some Senate districts in most outer suburban or exurban and a few rural corners of the Commonwealth that the Republicans won in 2010 and could with the right candidates and messaging win again and hold in the relatively long term. It would be easier if counties in this part of the country were actually meaningful entities, because I could easily see Republican County Commissions getting elected in Essex, Worcester, and possibly Hampden and in good years, and they actually do in Plymouth and Barnstable as I understand it.
You should also remember that Fall River, New Bedford, and Lowell are really only almost-within-reach for Republicans in statewide elections; both locally
and in Presidential elections they're pretty firmly Democratic.
Come to think of it, what about District Attorneys? I don't actually know much about that side of things.
I don't know locally, but I do know that Worcester County, Norfolk, County, Plymouth County, and Bristol County have been trending R at the presidential level recently.
How are you using the word 'trend' here?
