Okay, a lot to unpack here.
1. Since gE has been around this is the fifth, seriously fifth, round of Kraft "talking" about building a SSS.
2. I've heard people in Boston say that Kraft really doesn't want to build a SSS. Not only does he own the Revs and Pats and Gillette, but he owns the parking lots and the commercial development around Gillette. They don't do great but he keeps all of the money, everything, why would he give that away? I've been told he'll build if he doesn't have to pay for it.
3. That UMASS Boston site is terrible, not as bad as Foxboro but still really bad, hard for most in the area to access.