Database
[{"data":{"name":"Doe","values":{"AA_Avg":13,"BB_Avg":19,"CC_Avg":18}}}]
Query
db.collection.update({},{"$rename":{"data.values.AA_Avg":"data.values.AA_MT","data.values.CC_Avg":"data.values.BB_MT","data.values.DD_Avg":"data.values.CC_MT"}})