ESPN has a win probability tracker on GameCast for all of their games (at least the ones I have ever followed).
I would be curious to see the math that goes into it as there are times when a highly ranked team can be losing by double digits to an unranked team, and the highly ranked team still has a 75% + chance of winning. Granted said highly ranked team has stormed back to win by double digits many times so there is a precedent there.
Clemson had I believe a 90-something percent chance of winning their game against NC State on Saturday-only to give up an 8-0 run with something like 16 seconds left in the game. Lost by 2 on a last second 3 pointer.
Will never forget that crazy comeback Duke made almost 20 years ago to steal a win against Maryland.
https://www.youtube.com/watch?v=T9_pPqWfI84