To follow up on the discussion at Lawyers, Guns, and Money, there is exactly zero sense in projecting Stephen Strasburg's performance beyond the next three to four years. The history of baseball is filled with top pitching prospects whose careers end early (Mark Prior), never materialize (Todd Van Poppel) or who take years to develop (Adam Wainwright, Josh Beckett, etc). So there's no reason to put "future Hall of Famer" next to Strasburg's name; the odds of pitchers getting hurt is just too overwhelming.
That said, the case can be made that polished college pitchers can make it to the major leagues with less than a year in the minors and immediately become incredibly valuable pitchers. Mark Prior gave the Cubs three seasons of ace pitching within five years of leaving USC. So far this year, Tim Lincecum is pitching better than he was when winning the Cy Young. Considering the going rate for a staff ace is about $16M/year, signing Strasburg to a $20m contract almost makes sense. He may not last long enough to win 300 games, but he is likely to be highly effective big leagues for the next half-decade.
(Photo by Flickr user samballew)