From what I understand of the process, it depends on what comparable sales have been made. So if your neighborhood hasn't seen a lot of sales in the past few years, or what has sold has been less desirable than your property in ways that are not captured in the process (not sure how they keep track of upkeep or age of the roof) then your assessment will be lower than if a bunch of new condos very similar to your unit have just been built and sold. (I'm over near Trum and definitely saw an increase in our assessment after the MaxPac sales went through, and I expect some more possibly with the Cedar St new condos.)
no subject