So there isn't an AVGIFS function currently in SmartSheet, but I still need to find a workaround. I came up with:
 
=IF(AND([Project Manager]="Name",[Owner]="Name",[Project Status]="Complete"),AVG([Days to Complete]),"")
 
However I am coming up with a "MISSING OR INVALID PARAMETERS error. I have pulled the averaging portion out and it works fine on its own. 
 
Any ideas?