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The group system currently selects a pool of 10 players. If any one of the ten does not join (they decline, or time out) the whole game is scrapped.
The easy solution is to start with a pool of 12 players, not 10. As soon as 10 accept, the game begins. Those last two are placed in priority for the next game (if they did not decline), or dropped from the pool (if they declined the match).
This would greatly reduce the number of dropped games.