Re: Pak V NZ 2nd Test.
We do not know, but it is possible that all those innings he was not-out, he could have made century if he had enough overs to play, and then his average would have been much higher. Actually, making first 10 runs in test cricket is most difficult, but as a player progress into double figure (reached 10 runs), his scoring gets easy and getting out becomes difficult.
So, to have so many not outs at score above 10 runs are lost opportunities for a batsman.