The othere are drops that cant be pegged in any of RF reasons.
So it may or not be RF related .
Normally I see a high sudden loss drops , with following reasons
1Transmisson/T1 errors; Solution Fix the T1/Check if cascaded T1 are defined correctlu
2Faulty TRUs; run the mots report to find faulty TRU Or block one tru at a time to find the faulty TRU
3Incorrect IDB ; make sure that latest IDB is loaded in the BTS