The biggest downside to having a great coaching tree is when it’s time for the harvest. (That’s a fine metaphor, indeed.) Bret Bielema is famously part of the Hayden Fry coaching tree. Fry was the legendary Iowa coach that Bielema played for and started coaching under back in the day. Fry gave a lot of future coaches a job in his days at Iowa, including Bill Snyder, Bob Stoops, and Barry Alvarez, among others.
The good thing about having a head coach that finds great assistant coaches is the progress on the field and in recruiting.