The 2019 Big 12 was pretty interesting. When you look at both the results and advanced stats, there were some pretty clear tiers with Oklahoma and Baylor at the top, followed by a Iowa State and Texas, then probably Oklahoma State, TCU, and somewhat surprisingly, Kansas State. Then you had the other three first year head coaches with West Virginia, Texas Tech, and Kansas all struggling to figure things out while dealing with roster turnover and injuries.
After you hire a new head coach you can expect to see the most improvement, by far, in the second year.