Height requirements are issues and most really talented basketball players Don’t want to go to a service Academy anyway. They can only transfer out in the first two years.
This just doesn’t happen that often and even if it does, they don’t care.
With regards to football, it’s the same rules with regards to leaving within the first two years. They have always had a lot of guys leave. It won’t be that different. They generally aren’t recruiting high profile guys anyway.