Description of issue
I always suspected this was the case but never really experienced a situation where something occurred that would prove it, but it just has.
In a scenario where a shot occurs immediately following a first shot (eg. the first shot is saved but goes back to the attacker who shoots again), the second shot's xG should be "downrated" on the basis of the xG of the first shot.
Consider a scenario where a striker has a first shot with xG of 0.5, the keeper palms it back to him, and he has another shot with 0.6xG - the total xG for that scenario/"chance" is 0.85 xG (0.5 from the first shot, and 0.5 x 0.6 for the second shot ("downrated" by the % chance of the first shot being missed because it would never have happened if the first shot was a goal)). If you just add the two xGs of each shot you get 1.05 xG which is obviously not possible.
I just had a chance where the player had a series of shot from close range, the first ones were blocked but he finally scored. The shot map shows four chances with the following xGs: 0.03, 0.25, 0.42, 0.60, which totals to 1.30. I have uploaded a screenshot of the shot map but also the save game - the match is the last one that was played, Bristol City vs. Coventry. The scenario in question is the Jamal Baptiste goal on 65 minutes.
Owncloud file with save file is named "140223 xg bug"
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