So while the lower rate of change is no guarantee that things are good, the higher rate of change means that immediate action will need to be taken.
Likewise in systems, if a disk gets to use 80% of its capacity gradually, there is probably no need to panic. A careful plan will allow operations to ensure that disaster doesn't strike. If it spikes suddenly then there is a definite need to do something quickly before the system locks up or starts losing transactions.
Knowing that there will be an issue is even more important than recovering from an issue that has already happened.