Is there an explenation?

[Hankumata]

Gk with the man of match means you were trolled or your opponent was trolled.
And usually this happens after series of wins.

Thanks! I really think this is the explanation

[khris]

Thanks! I really think this is the explanation

This happens because of the rating variable. Your scorers* have a pattern in ratings, and they reach the Max which is 9-10 during few games in a row with Max performance.
After something like 9-10-10 a 7/8 will come, and this force the engine to select other players to be determinant when you need to resolve a match. In this case the MoM can jump to the GK.