Omaha has an elevation of 1,000+ above sea level. Washington sits at 400 BELOW sea level. That's a big difference when you are trying to adjust to 5,280 above.
that's true, but they're athletes who are in great physical shape. They shouldn't have a problem with it. It comes into more play in sports like basketball and football. A short spurt game like baseball doesn't affect it as much. They should be fine. If they were playing in Vail, or Colorado Springs or Fort Collins, I'd be more concerned, they're considerably much higher than Denver is.