Guy Kawasaki said, paraphrasing the point in the video linked above or in [1, 2, 3, 4, 5] (it was also in the biography, "Steve Jobs", by Walter Isaacson): “Steve Jobs has a saying that A players hire A players; B players hire C players; and C players hire D players. It doesn't take long to get to Z players. This trickle-down effect causes bozo explosions in companies.”
"The Claimant says he is “a computer security expert”, but his background and his track record in the education sense (genetics) does not support this assertion."