How different would it be if the person earned 13 points and if you lost 3 points? (Think of the difference between earning $13 and losing $3)

That’s a big 16 points difference ($16).

Because of that one person losing 3 points instead of gaining 13 points, the average decreases by 4 (if the points were to be spread around the entire team, then each member of the team would get 4 fewer points each).

Number of people
= 16 / 4
= 4

So there are four people.

If the person really gained 13 points, then the total score of the team
= 4 x 54
= 216

The 13 points gain did not actually happen, so the actual number of points
= 216 - 13
= 203

————————————

Or, if the person really lost 3 points, then the total score of the team
= 4 x 50
= 200

The 3 points loss also did not actually happen, so the actual number of points
= 200 + 3
= 203

Thank you. I have a clearer picture now.