SEC has probably 12 teams that can make the NCAA tournament. For a football conference they are playing pretty good basketball this year.
Some conferences have good years and other have down years, but they generally stay within a range. The SEC is pretty good this year, with four legitimate Final Four caliber teams (Alabama, Kentucky, Auburn, Tennessee), a few more Sweet 16 caliber (Florida, Georgia, Mississippi State, Mississippi), and a few more that will be fighting for bids. 15 of the 16 members of the league could go .500 in league play and get a bid, which is impressive, and even the worst team, South Carolina, is not bad. But despite having had such a strong year, the SEC is still only 17-12 against the Big 10, Big 12 and Big East, and the wins are mostly close, with only 6 of those wins by double digits, and 5 of the losses by double digits. But the SEC is completely dominating the ACC, with a 26-3 record against the ACC, and 18 of those wins by double digits.
The Big East is having a down year this year, and a down year means that it has maybe one or two Final Four contenders and maybe three or four teams that even have a reasonable shot at making the Sweet Sixteen. It has a team that is really bad, Seton Hall, that is picking up some bad losses and has another, Villanova, with a coach that is in over his head and loses to teams it shouldn’t lose to. It is still .500 against the other majors but has picked up a few more mid and low major losses than it should have. That is what a bad year for a major conference should look like.
The ACC is 14-43 against the other majors, and many of those losses are blowouts. By way of comparison, the A10 is 8-12. Over half the ACC is outside the Top 100 in the NET, and that includes some weird NETs like UNC which is getting rewarded for getting blown out by good teams. Less than half the league would get a bid if it went .500 in league play, and it is only the first week of December. That number is likely to go down. The ACC is looking like a 4 bid league, out of 18 teams.
The Pac 12 had some really bad years, but with the P4 leagues getting so big, you would have expected a regression to the mean, not one league falling off a cliff.