Per Kenpom, the difference between the Top 2 teams, is the same as the difference between 2 and 11. I'm not sure I've ever seen that.
Also, Kansas and Virginia are the luckiest teams in the Top 20, and Purdue is the unluckiest.
Rk Team AdjEM
1 Duke 30.58
2 Kansas 26.42
3 Virginia 26.24
4 Michigan 26.21
5 Nevada 25.64
6 Gonzaga 25.31
7 North Carolina 24.57
8 Michigan St. 24.28
9 Auburn 23.67
10 Tennessee 23.08
11 Virginia Tech 22.25
12 Texas Tech 21.73
13 Wisconsin 21.44
14 Florida St. 20.13
15 Purdue 20.11
16 Villanova 19.65
17 Kentucky 19.53
18 Syracuse 19.28
19 Iowa St. 19.2
20 Ohio St. 18.95
Also, Kansas and Virginia are the luckiest teams in the Top 20, and Purdue is the unluckiest.
Rk Team AdjEM
1 Duke 30.58
2 Kansas 26.42
3 Virginia 26.24
4 Michigan 26.21
5 Nevada 25.64
6 Gonzaga 25.31
7 North Carolina 24.57
8 Michigan St. 24.28
9 Auburn 23.67
10 Tennessee 23.08
11 Virginia Tech 22.25
12 Texas Tech 21.73
13 Wisconsin 21.44
14 Florida St. 20.13
15 Purdue 20.11
16 Villanova 19.65
17 Kentucky 19.53
18 Syracuse 19.28
19 Iowa St. 19.2
20 Ohio St. 18.95