Therefore, tournament NRR can alternatively be thought of as the weighted average of the run rates scored in each match (weighted by the lengths of the innings batted compared to the other innings batted), minus the weighted average of the run rates conceded in each match (weighted by the lengths of the innings bowled compared to the other innings bowled). Each time another match is played, the weights of the previous innings reduce, and so the contributions of the previous innings to overall NRR reduce.