First of all the Dolphins couldn't even beat Appalachian State. So your point is moot.
Second of all you act like 1 draft pick can replace 5 different players when obviously it cannot, whoever you pick. If I could draft Brian Urlacher in next year's draft, could he replace all 5 players? Absolutely not. So your argument is facetious.
Finally, the whole point is that if you have a chance to draft an outstanding top 5 stud talent for the next 10 years, you do it. McFadden, is one of those rare once in a decade talents.
Basically your argument boils down to - I am against drafting the next Bo Jackson because I am insecure about replacing many other positions in the future. That doesn't really cut it as proper drafting rationale.
In the case of the Patriots, thank goodness the fans are not in charge of drafting the team personnell. In the case of the Dolphins, I probably did a better job with my 2007 mock draft that I only spent about 1 or 2 hours researching. That just says so much about what a joke the Dolphins are from top to bottom.