"I highly doubt that the people making major league trades look only at this moment in time when making a trade as you suggest we do... i think they always look to what a player's potential could be."

I am not suggesting that we only look at the here and now, Obviously owners look at the future when they trade. What I'm saying is that trading is entirely about the assumption of risk. In your example (which isn't a good one because, forgetting the future, this trade isn't balanced NOW. For this example, let's theorize that this trade is being considered last spring) the risk one owner takes is that Smoltz goes back into the rotation and has a Randy Johnsonesque career curve, dominating into his early 40's. The other owner is taking the risk that Phelps & Wells will develop as the "experts" say. Equal, or close enough, risks to exchange. How the future works out has no effect on the fairness of this trade. The baseball graveyard is stacked high with cant-miss prospects that missed pitifully. Likewise players who were through have bounced back and had many more valuable seasons. To decide that big brother knows best and won't even allow these trades is wrong.
Please note that Mike allows these trades now. What I have a problem with is the people who confuse a fair exchange of risks with the outcome years into the future and who want to exercise 20-20 hindsight, complain and now favor curtailing trading to avoid this in the future.