It is like the Massey predicted losses column throughout the year - it adds up the 2% and 5% chance of loss in any single game and you end up with 2 projected losses even though you have a 90% chance of winning each individual game. The 52% is taking into account the total of all six games - so they have UConn with a 90% chance of getting to the final four and then about a 65% chance of winning each one of those games - when you add it all up it is still just 52%, but that compares to a 48% chance for the rest of the 63 teams in the field combined with Baylor at 23%, ND at 10% and SC at 8% so combined those three teams have only a 41% chance.