My theory for 2004 is:
I think that when Toa Vakama found the Vahi (Mask of Time) on Metru-Nui, he used it, skipping time ahead, to when Metru-Nui became Mata-Nui. That's why Vakama warned Tahu about the Mask's powers, and why the "outer shell' of Mata-Nui broke into Metru-Nui, and why the Turaga Toa are now Turaga. (Their destiny was fulfilled in the time they skipped.)
OFF TOPIC: Whoo hoo! I've defeated the "Mail Error" messsage!