Whether it is because Kansas has recently waded into the one and done market, or because impact Freshmen get so much ink in basketball circles, one thing that often gets overlooked in projecting conference races is frankly how much talent a team has returning from last year. Players, more often than not, either get better or stay at the same ability level as when they enter a program, so it's fairly easy to project how good a team "should" be based off how many minutes they have returning.
Enter our chart, which plots the percentage of minutes returning (I have done my best here. The transfer database I am using is ESPN's, but it may be missing a transfer here and there, so if the returning minutes section is off a bit, I apologize.) compared with how good the team was a year ago. I went with KenPom rating over conference efficiency margin because, while the latter narrows things down to only games against each other and takes out the adjustments of KenPom, KenPom rating covers a larger sample size.
After taking a quick moment to yell at West Virginia, Tech, and TCU for ruining the aesthetics, we see why people love Texas. They return everybody from an already pretty good team, and they add Myles Turner to their front court. Iowa State is probably a bit underrated as well: they return more minutes than I expected, and while I think he was good, Melvin Ejim is a replaceable player.
Of course this chart doesn't capture recruits or transfers: Kansas has an elite recruiting class, and Iowa State, Oklahoma, and Kansas State are all expecting impact transfers. I think Kansas is the favorite to win the Big 12, but this chart paints a picture of a more muddled race.