Note that market street around the Twitter building has never been a great area of SF. I think part of the hope was that it would re-vitalize that part a bit. Moving around SF is weird because the difference from street to street can be huge.
I didn't live in SF, but I flew there several times a year for over a decade. Market Street definitely saw a huge decline over that period. By the end, coworkers were refusing to walk it anymore for safety reasons.
