I would have thought there's a good chance the some of the other 7 promoted players would have been on multiple season academy contracts but seeing as its all within the same club, the contracts can easily be converted to a senior one, so why hasn't Umaga's?
How long has Umaga been in the academy? I can't see any player wanting to be stuck in an academy for more than 3 seasons (possibly 2) and I would have thought similarly a club will either jettison or promote a player after that time period as well.