You don't have to listen to IK. The former additional secretary of the ECP, Afzal Khan, already clearly stated that they were massively rigged (using different words, but the meaning is the same: widespread rigging took place.)
Is Afzal Khan a truthful man? Then the elections were massively rigged.
Is Afzal Khan a liar? Then the second in command of the ECP is a liar and that means the organization is not trustworthy; we can't be sure the elections were not massively rigged until we open the ballot bags and investigate.
In our Constitution, it is the responsibility of the ECP to manage elections in such a way as to ensure that they are free of rigging. Clearly they did not do this.
Which politician denies that lots of rigging took place? None of them. They accuse each other, that's all.
IK gave evidence: he presented more than fifteen witnesses to rigging at the Election Tribunal hearing. He can't do that all the time when reporters asked him.