This is just another way of saying that there is no such thing as a bad deal because whatever return comes in a trade is what the value was for that player.
Was Toussaint's value Gosselin and $10 million? I would say not even close.
Using your logic, we can't ever evaluate a trade. You just take it and accept that you couldn't get anything more. I think we could have gotten more for Wood and Peraza. But here's my point - even if we couldn't, then don't trade them. They have more value to us at that point than their return in a trade. I would rather have Wood and Peraza going forward than Olivera, Paco, Bird, and a pick.
You are making an assumption that they have more value to us based on the premise that a) Wood doesn't fall off or get hurt, and b) Peraza adjusts to the big leagues despite his lack of power and walks.
Personally I thought Peraza would have adjusted but I just dont' like Wood long term.