Ole Miss has an overall losing record which makes them ineligible for an at large bid. RPI, SOS and all that other stuff is rendered moot. Auburn only won 8 conference games. Historically, for the SEC the “floor” has been 13 conference wins (I believe one team made it in with 12 at one point). So despite SOS, RPI and all those other things, there ARE some criteria related to overall wins and conference wins. Obviously, not everyone agrees. Some feel there is SEC bias and others feel the metrics prove the SEC is the strongest conference by far. Both are likely true.
If going .500 or above in your conference was part of the criteria, the 5 SEC teams that are top 8 National seeds and Miss St. (who many thought should have been the 16 seed) would be the only teams to make the tourney. Usually, the SEC is more balanced than this year. But when 5 of the top 6 teams in the country are in one conference (and 4 of the other top 9 are in one other conference) you are going to have some REALLY good teams in those conferences that have losing records within the conference. It wouldn’t really be fair to be in the SEC and have to be top 16 in the country to make a tournament of 64 when the Big 10 Champs are number 50.
Now, we got screwed ourselves a couple of times in the past in all three major sports by “people in the room” so that is definitely a part of the problem.