Sean Bielat has two opponents in the primary. One is Elizabeth Childs (who styles herself a social liberal and fiscal conservative), who was apparently recruited by the MA GOP. The other is a conservative (a dentist, I think, from Fall River maybe -- never heard of him before). I don't know why the other self-styled conservative got into the race, but it looks like the conservative vote will be split.
If the GOP intended to recruit a "moderate" Republican who could actually beat Bielat, they wouldn't have chosen Childs, a former democrat and a Hillary voter who only registered as a Republican last year. Bielat is significantly ahead of both primary opponents last time I checked.