I think the Big 12 suffers from one major issue - the schools in this conference other than KU often suffer from a good coaching not having elite players, or elite players not having a good coach.
Huggins is a good coach. WVU has good players, but not any elite ones. That hurts come tourney time. Last year Lon Kruger had a lottery pick. He rode that team to the Final Four. This year he has nothing. We all see what happened.
Jamie Dixon is a good coach. He's at TCU. No NBA talent there.
Hoiberg was a good coach at ISU. Can anyone think of any lottery picks that he had?
Part of that is that the Big 12 conference footprint doesn't have a ton of basketball talent aside from Texas. There's just not a lot to draw from as far as local NBA caliber talent.
That makes it really difficult come March. The Big 12 has lots of really good college teams, but you have to raise the talent level to match that on the coaching side of things (the Big 12 has, top to bottom, probably the most coaching talent of any league). Who has the most talent in the Big 12 consistently? KU of course. Is there any surprise we dominate the league? We have the most talent and generally speaking, that is a huge difference.
Let's look at the three major games (McDs, Jordan Brand and Nike Hoops Summit) and check the rosters to see how many are committed to Big 12 schools:
McDs - 2, Billy Preston (Kansas) and Trae Young (Oklahoma).
Jordan - 2, Preston and Matt Coleman (Texas).
Nike - 1, Lindell Wigginton (Iowa State).
Think about that for a second. Out of the players considered elite, the Big 12 has four (4!!!) that are committed to play in the conference.
Flip over to the ESPN 100 recruiting. Let's look at the top 50 players.
Zero top 10 recruits heading to the Big 12 so far, although 4 top 10 players are still uncommitted.
2 top 20 recruits coming to Kansas (Preston) and Oklahoma (Young).
Coleman (ranked 27) heading to Texas.
Wigginton (ranked 42) going to ISU.
That's it for the top 50.
Here's the rest of the hundred - 58 (Terrance Lewis to ISU), 61 (Marcus Garrett to Kansas), 66 (Jericho Sims to Texas), 68 (Zach Dawson to Oklahoma State), 74 (Royce Hamm to Texas), 89 (Derek Culver to West Virginia).
10 players in the top 100 are heading to the Big 12, with two each to KU and Iowa State, three to Texas and one each to Oklahoma, Oklahoma State and West Virginia.
The SEC has 20 top 100 guys going to 9 different conference schools.
Pac-12 has landed 18 going to 9 of their schools.
The ACC has 16 going to 9 schools.
Even the Big 10 has 12 going to 8 schools.
6 schools in the Big 12 split 10 top 100 guys. That means nearly half of the conference is missing any top 100 talent. Three quarters of the Pac 12 has top 100 talent. The SEC, ACC and Big 10 are all bigger, but they have 8 or 9 schools getting top 100 talent, which means the top of their conferences boast more talent (although the Big 10 is pretty thin talentwise, but we saw what happened to that conference in the regular season).
Simply put, the Big 12 isn't getting enough talent into the conference, particularly at Oklahoma, Iowa State and Baylor, 3 schools that have done well enough recently enough to compete for recruits. You can't expect to compete at an elite level if you lack elite talent. Just ask the Big 10, the conference most comparable to the Big 12 in terms of incoming talent, about how that's working out.