If you set the bar at 85 points it wouldn't happen often. Fulham would have replaced Southampton last year- Huddersfield Town being safe. Derby County would have replaced West Brom in 2013/14, although Hull City would have survived.
It's not common for a team with less than 38 points to stay up.
You know, I quite like that. A standard three relegated but no-one can assume safety until they pass the magical figure.
Would never get off the ground but a good thought.