Can't find the reference for Ball being denied interview requests from outside the organization. Might have made that up.
But one thing I was reminded of going back, Ball's connection inside 1265 is to McCarthy. Ball worked for the Chiefs with M3, got suggested to be the cap guy for the Saints via McCarthy and probably got a recommendation in GB from him.
Ted and Murphy clearly fell in love with him as he has kept accumulating responsibilities, titles and salaries. But Ball could be the most likely to hang on to McCarthy.