Do you have a link to prove this? I find it a little funny that "many" people had Raymond listed as a first round pick yet he dropped all the way down to 51 overall. You'd think one of those "many" people would have drafted him earlier wouldn't you?
Regardless, does it really matter what Lowe thought about Raymond or Cogliano around draft day? Lowe once thought Niinimaki would develop into a star in the NHL and he hasn't even gotten a sniff yet. Thoughts on the players around draft day really mean absolute crap right now - all that matters is how they have performed since the draft. Given this, Cogliano is easily the far superior prospect given that he has outperformed Raymond despite being 2 years younger.
When I say many people, I am referring to Kevin Lowe and the Edmonton scouting staff, who would have briefed him. Go search the Vancouver board if you want the actual link. I already told you I cannot.
At this point - since draft day - Cogliano and Raymond have developed quite similarly. To say that one or the other has developed far more then the other is just incorrect. Thus, Lowe's, and the Oilers scouts rankings of the two, still holds water considering each has developed rather evenly. It is not like Raymond has developed worse then expected, which is the case in your example of Niinimaki - which doesn't resemble this situation. The age difference is also rather moot because Lowe and co. were obviously aware of this when they made their assessment. To answer your question: Yes - it does matter what Lowe and co thought, in fact, it matters a hell of a lot more then your analysis of the situation.
Yes, I do think it matter what professional scouts think about prospects on draft day. Cogliano and Raymond have put up similar numbers since being drafted, whilst it has already been pointed out that Raymond plays in a better conference and plays on a terrible team in which he has little to no supporting cast.
I really don't know how you are going to win this argument. I think it is fairly obvious that if an organization believes that two prospects are of similar ilk - then it would appear quite silly to say that for one to surpass the other it would be a "massive surprise", unless you have some egocentric opinion of yourself which makes you feel you are a better talent analyst then a group of professional scouts.