USC basketball has been lost for years, decades. With the exception of one three week hot streak with a bubble team that nobody saw coming in their wildest dreams. Some decent days in the old Metro. A couple of good years under Fogler, but then they melt down in the tourney. The hole USC finds itself in was actually created by Paul Dietzel decades ago. He was able to convince the powers that be that the only way USC could be elite in football was to leave the ACC because of their academic recruiting restrictions at the time. Frank tried to tell anyone that would listen that pulling out of the ACC would kill the basketball program. And he was correct.
McGuire didn't publicly fight leaving the ACC because he thought the program was on solid enough ground, and the Athletic Department needed to at least put on a public display of unity (McGuire & Dietzel did not get along; IMO, when Rex Enright retired circa 1960, USC should have hired an AD who did not coach any varsity teams and made that a policy going forward).
Of course, it took only a year or two of independence for it to be obvious to anyone truly paying attention that leaving the ACC definitely hurt the men's basketball program (no varsity women's sports were around at that time).
It's important to note that Roche & Owens would not have considered enrolling at USC if we were not in the ACC. And USC lost many potential blue-chip recruits during our years in the wilderness.
I had a bad feeling when the 1971-72 hoops schedule was released and Clemron was the only ACC school on it. When the Tar Holes took us to the woodshed during the 1972 dance, my gut told me we were on our way down.
The irony of the whole situation is that the fan base got riled up to leave the ACC only because of the basketball discord. Had McGuire taken us to the top of the ACC without a chip on his shoulder, I think Dietzel would have had a hard time convincing anyone to go independent.
Of course, none of this explains the current success of the women's program. The OP did not specify which basketball program in his/her original message, which is why I'm addressing both programs.
The bottom line, I believe is this. Your school has to have an excellent coach in a high-profile competitive conference to be successful. Pretty obvious. By excellent, I mean a coach who is a good recruiter, a good teacher, and a good mentor, someone who many would want to play for, and their parents would be thrilled to have coach their daughter/son. We are very fortunate to have Dawn Staley. Sadly, not so much with Frank II.