BJP owns the election commission with appointment of all of its cronies and gujarat cadre officials in it. And its done subtly.
Some places where BJP is famously weak, votes go to independents. Where its a tough fight, its set in a way to cover the divide just enough to get the bjp guy through. In places with its important leaders, its tweaked for huge margins. In places of big opposition leaders, its tweaked to add votes to reduce their margin of win and make opposition leaders seem weak.
ITs done in a way to ensure the results themselves dont show tampering in an obvious way. And the tweaking is just enough- like 10-15% margins, never more to keep pretence of public mood being visible in results..