Quite a few things to consider:
1) for average calculation, you don't take +/- Par but the gross scores. Difference: Up to two shots. There's no additional influence in strokeplay games.
2) It's essential to know whether your average is saturated or not. Above 500 Legend scores, only the 500 best scores count and the average can only drop or stay. Below that number, it's floating.
3) Important to know if it was a 9 hole or 18 hole game. 9 hole scores are doubled which may increase the effect above tremendously. -4 on OLY front nine is 30 => 60 score, having a good influence on your handicap of 64.36. -4 on STA full course is 68, negative or nil influence.
4) as a Legend, the pool of numbers may become very big, up to 500 scores. The average will roughly move by the difference of the new score to the average or the highest saved score, divided by 500. The minimum move is 1/500 = .002. Therefore, a change in calculation may be invisible to you if it's less than .005.