The caste order written into scripture and the order that actually operates in a village are often not the same thing. Locally, rank follows who owns the land. So people who sit high on the textbook ladder can end up as clients of a landowning group ranked lower on it.
A group can gain wealth or power without gaining matching ritual standing. When that happens, it tries to raise its rank by taking up the customs and habits of the groups above it. Over time it lays claim to their position by living the way they live.
Relations between groups ranked by birth are carefully regulated and bounded, yet in everyday life they keep shifting and being renegotiated. To understand such a system, you have to watch the day-to-day dealings between neighbours. The formal rules alone will not show you how it works.
Practical power in a community rests with the group that combines land with large numbers, whatever its formal rank. That group supplies the headman and the leading families. A small but formally superior group can end up deferring to it. The same pattern can help explain prestige in quite different settings, such as which unions carry weight within a labour movement.