Can it be right to defend your blind 84% of the time?

[trojanrabbit]

Let's say you're in the BB and it's folded to the SB who raises to 3BB. You know that he will raise on the top 50% of his hands. If this were an all-in bet you could figure out mathematically which hands you should call with and it turns out to be about 84% of all hands (including hands as poor as T5o and 53o).

But let's say it's not all-in and you both have deep stacks. How should you adjust your initial guess of 84%? Many of the unsuited hands will have reverse implied odds making them less attractive when there are more bidding rounds. But your opponent will have a lot of reverse implied odds hands as well, so maybe you shouldn't trim your list down by too much. But also consider that you'll be in position for the rest of the hand. Shouldn't that make you want to call more often because you'll be in an advantageous position?

Is it really right that you should be defending your blind on T5o and maybe even weaker hands? Is there a flaw in my logic?