When an Active Directory Organizational Unit (OU) is deleted in on a Windows 2012 Domain Controller and the "Delete Subtree" option is selected, there are no events generated for the objects that were deleted within that OU. The only event recorded is that of the deleted OU: "Subordinate OU Removed".
If an Active Directory Organizational Unit (OU) is deleted in and the "delete Subtree" option is selected on a Windows 2008 Domain Controller, delete events are recorded for the User and Computer objects that were contained in that OU.