Every system of ranking has its own bias and limitations.
Same is the case with the ranking of BITS Pilani. BITS Pilani is an excellent Institution in India and this can be confirmed from the academic environment at BITS and the students there. So, if you’re convinced of the academics and other parameters of BITS Pilani, please go ahead without any doubt, provided you really are interested in pursuing the course there.
Another example is, even colleges like IIIT Hyderabad, IIIT Bangalore and IIIT Allahabad don’t really have a great ranking. But in reality, these are excellent Institutions to pursue CSE and ECE.
So, the conclusion is, don’t rely on any ranking authority. Research yourself on faculty, academics and the other parameters of interest. Check on LinkedIn what the alumni do. Speak to some alumni and current students. And if you’re convinced, irrespective of the ranking, go ahead.