My thoughts on this is there is a "time factor" at work, and it varies from state-to-state.
In places like New York, New Jersey and Connecticut -- where the virus exploded "early on" -- the death rate was higher (in part) because a few months ago less was known on how to treat the disease, particularly among the old, frail and very sick (not to mention Cuomo's policies in NY state).
By contrast, at the same time other states in the midwest, mountains, south and southwest were barely at the "foot of the upward curve", with few-to-no cases present. But this is changing as these states now experience their bugeoning of infections. However, the body of medical knowledge has expanded to a point where more is known about how to treat it. Hence, fewer deaths.
Here in Connecticut, new infections still occur but not at the high rate of two months ago. Just checked the numbers a minute ago while composing this post.
Today, we had 81 new infections statewide and 11 deaths.
My latest numbers for Fairfield county -- 39 new infections and 5 deaths.
Here in town, 0 new infections the last day reported, 2 the day previous.