NCAA bracket trends show that 9 through 12 seeds in the NCAA men's basketball tournament are where you can look for most of the first round upsets to occur. A number 9 seed beating an 8 seed really isn't an upset, in fact 9 seeds hold a 50-42 advantage over 8 seeds since 1985. But when a 10, 11, or 12 seed wins in the NCAA tournament then we're talking upset.
9 thru 12 seed NCAA bracket trends since 1985:
9 seeds are 50-42 against 8 seeds.
10 seeds are 37-55 against 7 seeds.
11 seeds are 29-63 against 6 seeds.
12 seeds are 29-63 against 5 seeds.
The summary below shows how far 9 thru 12 seeds have made it in the NCAA tournament since 1985: