Elevation really has nothing to do with total climbing on a particular course. Missouri is a perfect example of that. While there are few sustained climbs for any distance, Missouri mainly features repetitive short & steep (10-20% grade) hills (no real "mountains"). The hills get steeper the farther south you go. While most maps and mapping software (and people for that matter) will wash it out to "flat" (again elevation measure alone or measuring ascent/descent), the total amount climbed will sneak up quickly. To use an example, I had the time to map out stage 2 of the 2009 Tour of Missouri out to Pocahontas. 81 miles, about 2402 ft of climbing, total. I notice a couple of good sustained (for MO) climbs they put in there.

So in essence, while you can find what genuinely qualifies as "flats" in Missouri, it is equally as easy to find the shorter climbs. While this is obviously not a concern to the riders of the Tour of Missouri when it comes to conditioning, what would present a challenge to them in gaining a fast time is the short repetitiveness of these hills to be able to adjust from climbing to descending. But keep in mind, too, that they are finding enough "challenge" (climbs, flats, whatever) to make these pro riders believe that it's worthy of their time.

I don't know if that answers the question, but hopefully it does.