This is what I feel happens in equating methodology:
(Totally my opinion. No intentions to defame or bash VIT)
They kind of take relative performance too seriously. Meaning, if people in your center giving the exam are weak or below average performers and you score relatively better, their methodology would consider the paper to be tough and you to be a relatively better performer, which might not actually be the case.
When I gave the exam, people around me were literally not interested. Some even left an hour in advance, while I was a bit serious about the paper and tried to attempt it fully. I'm pretty sure that I scored much better than the folks around me, but I am also sure that I could have barely scored 120 marks.
PS: My rank 4982