I don't know what drives this particular rating, but having the defending national champion (with a known, national basketball brand) plus 4 teams in the Sweet 16 this year has to help bring eyeballs, I would think.
On top of that, the Cooley to Georgetown move received significant attention. Maybe that is more "niche" or "regional", but I feel like it was a pretty big story and him being at another recognized brand should help.
Last, there is the "Pitino-factor". Having him trying to rebuild NYC's team is a big deal, not just locally. And if he wins at all that will have legs.