Since the Kenpom rankings began in 2002, almost every champion had a top-15 offensive efficiency and a top-20 defensive efficiency. Many were top-10 or top-5 in one or both.
Here are the national champions since 2002:
AdjO AdjD
top-15 top-20
2002 Maryland X X
2003 Syracuse X X
2004 UConn X X
2005 UNC X X
2006 Florida X X
2007 Florida X X
2008 Kansas X X
2009 UNC X X
2010 Duke X X
2011 UConn O X (#19)
2012 Kentucky X X
2013 Louisvillle X X
2014 UConn O X (#39)
2015 Duke X X
2016 Villanova X X
2017 No Carolina X X
2018 Villanova X X
2019 Virginia X X
2021 Baylor X O (#22)
2022 Kansas X X
2023 UConn X X
This year will be no different:
UConn #1/#4
Purdue #3/#12
So if you want to be a national champ, you'd better be really good (not just good) at both ends of the floor.
Alabama #2/#111
NC St #48/#38