In 2017, all the NITS saw a drop in their cutoff ranks. The reason was the removal of class 12th boards percentage from JEE Mains rank calculation.
Here is a simple example to get my point across-
A-1, B-2, C-3, D-4, E-5, F-6, G-7, and so on.
C-1, D-2, E-3, B-4, F-5, A-6, H-7, and so on.
Now, A,B,C took the 3 seats in IITs, and D,E,F got into NITs. So, the cutoff for IITs was 3, and that for NITs was 5 ( as F was the last one to get into NIT, with rank 5 in JEE Mains).
B-1, D-2, A-3, C-4, F-5, E-6, K-8, and so on.
If A,B,C took IITs, and D,E,F got into NITs, the cutoffs for NITs was 6 ( as E with rank 6 was the last person to get in).
Here, the cutoff went down by 1 rank. But when lakhs of students attempt an exam, such a change brings down the cutoffs by hundreds and thousands.
This is the reason why MANIT Bhopal cutoffs went down from that year.