This is not a good use of numbers, yikes. The vast majority of top 30 teams will have good offenses. If teams only played good offenses their defenses numbers would be .
And he's comparing raw D ppp vs. adj defensive efficiency. Mississippi Valley St is the only team that gave up 1.23 ADJUSTED efficiency. A lot more teams gave up raw 1.23 ppp. And if teams only played top 30 teams, I imagine a large percent would give up 1.23 raw ppp.
Using Torvik, St. John's adjusted def efficiency against those teams is 1.05. About 200 teams had worse numbers than that last season against full schedules. (Edit this might only include 2 of the games, I think the regular Torvik stats are updated but not the sorting stats).