I've seen MSU listed at 11th and 23rd for SOS.
So depending on what's measured, it's a top 25 difficulty schedule.
As for how we aren't #1...i don't know who is, but I can say that thru the season it's seemed like Houston, Iowa State, UCONN, Baylor, KU, have had really tough schedules too.
...and that's just listing non-SEC teams.