This is not REALLY the case. Michigan didn’t retain their most important guys. Burnett was a returner but also a transfer who was at Bama and TTech. Other 4 starters were transfers this year. McKinney was a freshman. Gayle returned from last year but was also a transfer last year
PSA:
Not every commitment during Transfer Portal season is a "great get".
High volume DOES NOT guarantee a large number of wins for the following year.
The 4 teams that played in the Final Four all retained at least 4 key players from the prior season.
Retention > Addition.