I think that's the right answer.
Bring in 25ish HS kids each year and hope to create strong coach/player & player/school relationships in hope they develop as players and stick around.
But the other reality is kids are always in the portal to be recruited. Using Manske as an example, even if Campbell stayed, it wouldn't have surprised me if schools like A&M or KSU didn't take another run at him.
Going forward it wouldn't surprise me if Iowa State is successful, that around 25 players enter the portal each season. Losing around 10-15 first/second string guys to more money and 10-15 bottom of roster players because they won't play