I guess my question is that the reason Manning or Brees wouldn't make the playoffs with a complete rate of 38% downfield is that that's not their scheme? That doesn't necessarily mean they are better quarterbacks than others in other schemes, as the other guy mentioned, Tom Brady, just gets it done (most of the time) with the little tools he has. If he had a Harrison or Wayne as a down field threat, you don't think that his completion rate would go up?
I see what you're saying and I mainly agree, but I'm not sure (only because I've never played quarterback, and certainly not at the NFL level) that spread offense has more pressure than a West Coast precision offense or the reverse of that. The statistics don't seem to support your argument but instead seem to say that these guys are good in the schemes they are in.