What does (deaths / (resolved + deaths)) describe in an emerging epidemic?
The problems with the measure you've proposed have been addressed on MedicalSciences.SE:

https://medicalsciences.stackexchange.com/q/20970/8728

The short version is that this measure isn't very informative while there are unresolved cases, because it ignores what is known or expected about those unresolved cases, and it is not a standard measure.

In the long run (when almost all cases are either recovered or dead) it approaches the case fatality rate because the denominator of (resolved + deaths) becomes equal to the total number of cases. Until then, it doesn't tell you much at all.

You could track the case fatality rate over time based on time of initial diagnosis to look at effects of new treatments.