All the scam/controversies/blame-game etc aside. At a national level it makes sense only if bank is lending at say 10%, can they give you a deposit rate of 9%. If, for whatever reason if they are able to lend only at 8%, they of course will give returns of 7% on deposits.
Ofcourse that may not be the only way banks make money - but that is the reasoning behind the change.
I mean I wont claim to know what they do or dont do. But in theory, the level of drop should eventually be closer. Not a market expert to comment for sure. The interest rates of atleast home loans have dropped a bit in the past - so some drop in deposit rates was sort of expected by me. How much is fair and whether the ratio is correct - not sure.