If you select a trade lane in the above example, and hover over one of the time bands, a Drillthrough link is displayed:
Parcel Details tab
If you click on Drillthrough, the parcels that were delivered during the time band are displayed under the Parcel Details tab, e.g.
This view allows you to to compare delivery with the SLA Target Days (the link in the example was for parcels that took 4 days to be delivered and so they all missed their target). It also allows you to see by how many hours each parcel was delayed between its Guaranteed Delivery and Actual Delivery Date, and the postcodes to which they were delivered. This is information that you can take up with the carrier.
You can use the Order Numbers and Consignment Codes on the left of the tab to identify the packages in Metapack Delivery Manager.