The years I have listed show how many points the team in 20th place got. The point I was making was that in a number of seasons they would have still achieved 20th place with a lower points total (because of the difference in points achieved by 20th and 21st place teams) and in 1 season with 5 fewer points. As stated an average of 48.8 points was needed over the 10 year period to finish in 20th place the fact that the average points achieved is higher is inconsequential.
This I why I compared our promotion winning season as we would still have won the division with 87 points although we got 99. Similarly Liverpool did not need 99 points to win the Premier League last season as they would still have won it with 82.
I see no problem in aiming for 50-51 points but I suspect we will achieve safety with a lower points total.
I suspect you are wrong.
Time will tell I suppose.