Complex sentence: Just as explained in the scenarios above, the NRR is not the average of the NRRs of all the matches played, it is calculated considering the overall rate at which runs are scored for and against, within the whole group.
Split into simpler sentences: Just as explained in the scenarios above, the NRR is not the average of the NRRs of all the matches played. It is calculated considering the rate at which total runs are scored for and against, within the whole group.