I can only speak for college golf teams.
For our school and other schools, joining the team as a walk on was a very rare case. But it has been done. One kid shot around even par for 4 rounds from the tips.
It happens occasionally in Football but hardly often. Carl Nassib for Penn State was a walk on & led the nation in sacks this year. The guy is a freak athlete (6ā 7" 270 with speed) which I will assume ACE is not (no offense ACE)