Some of SV's biggest tech companies and institutions started in Boston. Reddit was in Davis, Drew started Dropbox while he was still at Bit9, Zuckerberg was in his Harvard dorm with staff meetings at Pinocchio's pizza. Hell I used to live next to the original YC office in Cambridge.
The talent exodus and missed deals was a huge wake-up call for Boston VC's to take more risk, and I think we're finally seeing the results.