Reporting of Operational metrics at the Email level, as opposed to the Incident level

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Has anyone had any luck reporting on emails at the transactional level, rather than at the incident level? Would like to create a report that will shows metrics such as Email Volume (Not Incident Volume), Average Speed to Respond (ASR), Average Handle Time (AHT), Service Level (SL). All OOB reporting for email seems to be crafted for Incident level reporting, and relevant to the initial incident. 

Would like to know how to calculate these metrics relevant to every email interaction within an incident, not just the full life of the incident. Especially when attempting to leverage such reporting for Workforce management purposes. Seems like a pretty big gap in the reporting offering.