Certainly that was the case a few years ago when things were booming. Some retailers moved out due to high rents (e.g. Ecco Pizza gave that as their reason I think) while others, especially those who have left more recently, have been hit hardest by the lack of consumer spending. Given the increasing number of vacancies on Rokeby Rd, some remaining empty for more than a year (e.g. the corner surf shop opposite Dome), I would imagine that the rents will have been dropping for the past few years down from their lofty heights during the boom.
There's been quite a high turnover of retailers as a result of the difficult times/lack of consumer spending. I think clothing retailers have been struggling the most while food retailers have fared a bit better. A pick-up in conditions hasn't occurred yet – I'd say the number of vacancies is probably highest now than I've seen it in the past 6 years.