I don't think that changed this year. Big West adds volleyball next year, right?

From Wikipedia:

Through the 2013 tournament, each of the three major conferences (MPSF, MIVA and EIVA) received an automatic bid to the Final Four, with one additional at-large bid. The remaining bid was an at-large bid that could be awarded to any team in Division I or II (including Rutgers–Newark). Generally, the best team not receiving an automatic bid (usually from one of the three major conferences) received the at-large bid.

Beginning with the 2014 championship, the field expanded to six teams, with the two new teams being the champion of Conference Carolinas and one extra at-large entry.


https://en.wikipedia.org/wiki/NCAA_Men%27s_National_Collegiate_Volleyball_Championship