That is not entirely correct. There are other factors in play as well - what specifically is something that no one apart from EK knows fully. I know of a specific case on EK203 departing from DXB where there were 6 of us Plats in J and only 3 of us were upgraded to F. Another Fter was with me at the J lounge on that flight and he had already accrued more than 150K tier miles after his qualification on 1-Apr while I had accrued <50K. I was among the 3 to be upgraded before the F cabin became full. More info here (post #19 onwards).
http://www.flyertalk.com/forum/emira...erience-2.html