Before that prospect becomes a factor the team could have traded for a player to fill the role or have had another, older prospect develop to fill it. If the team finds that they are overloaded in the position that they choose the 'best available player' in, his trade value will be much greater than that of a lesser player who was drafted for position. After the first three rounds however I recommend throwing this principle aside. The draft become a real crapshoot at that point and instead of choosing second tier players who are unlikely to become anything more than minor league fodder I would stock up on 'special choices', even if it means ignoring players who are currently superior in ability. More gems from the later rounds come from Europe than anywhere else as it is very difficult to get accurate rankings and information on player development from those countries.
Goalies are notoriously hard to handicap and are often late bloomers.
Again it is harder to get an accurate reading of players in these leagues. And in the case of NCAA players you get the liberty of a longer development period to be sure. Now's the time to take a chance on a Doug Gilmour or Theoren Fleury type. He got injured early and missed almost the entire season. Many have forgotten about him.