The problem in a lot of care homes, is that simply, carers do not notice the deterioration in our loved ones. Maybe because they see them every day or almost every day they don't notice the changes. If someone sleeps a lot or, loses their appetite it won't often raise alarms even though we may know this is not "normal" for them.
I have seen so many residents deteriorate and sometimes it is due to underlying illness, boredom, under stimulation, dehydration and the list goes on and on. If you are concerned, you should ask questions and not just accept their reply that it is normal progression of the illness as sometimes it isn't.
Remember, nobody knows our loved ones better than us.