Channel 7 did give her a job in Adelaide: http://saweekender.com.au/presenters/belinda-sloane
There are a lot more people in Melbourne than Adelaide. Therefore channel 7 get more viewers when the Vic teams are doing well, more so than the interstate teams. Therefore, "promote" Belinda to Melbourne in order to get Rory to follow her across the border to a mid-table Melbourne side like St Kilda to give them a boost up the ladder and bingo - more ratings.