Now before we continue we are running under the assumption that your team has run tryouts so that the youth on your team have earned the right to be on your team.
Thesis: Youth will get you to big moment, Experience will make sure you capture it
The best example of the youth getting them to the finals were defenders Drew Doughty and Duncan Keith. In the Preliminary stages of the tournament and the pre-quarters, quarters, semis. Doughty and Keith were the standout defensemen for the Canadians. Throughout the tournament elder Statesmen Chris Pronger was drawing criticism from many for his sloppy defensive play and at times idiotic penalties. Yet come the Gold Medal match, Pronger and team Captain and oldest defensemen Scott Niedermeyer, were the top players on defense for Canada. The experience that these two players brought allowed them to excel in the big game
How this applies to ultimate.
Early in games and tournaments allow your youth time to play and make plays. Youth brings energy, exuberance and a desire to prove that they deserve playing time. Late in tournaments, late in games, go with the players that have been there and wont be bothered by the big moment. That is , if they are still able to perform at their best. Go with experience, but dont cut your youth out altogether, give them chances to still make plays and prove themselves, but lean more towards experience.