I guess SR is interested more in punctuality than faster trains. That is why they are giving the slack there by slowing down. If you look the running of kerala express, 3hr late at BZA, by the time train enters Kerala, it will be on time. LPs will be just operating the train as per MPS of track on normal day as well as on late running days. But still it will make up the time due to slack. In one side, we can say train is running on time, in other side we can say, train could have reached faster.