The Dinkins race was known for another issue; since his last race they no longer project winners earlier on election day because of the reaction as the day went on that he might win. Voters jammed the polls later in the day, and his loss was attributed to the projections throughout the day motivating his opposition.
He really was a horrible mayor; the city lost a large number of whites (especially Jews) during his tenure. I don’t think the city has ever recovered.
Dinkins behavior during the Crown Heights Riots, where he allowed rioters to rampage through an Orthodox Jewish section of Brooklyn for three days, was reprehensible. He convinced white voters that a black mayor would never protect them from black crime.
New Yorkers realized that having a black democrat mayor for another term would likely irrevocably send NYC into the same decline that Detroit experienced.