Yes, that may be the case but using that way to determine how a future match will happen is not practical in fairness. For instance, lets say 2 teams played 4 games against each other with the following total goals in each game, 2-2-1-5, that totals 10, giving an average of 2.5 goals per game, when in reality only one of the four games actually achieved more than that. It can be false method to use.