No, but this is for starters who were younger than 25 during the entire year in which the outing took place:
http://i.imgur.com/FZblwT2.png
Top five were starts made by Danny Salazar (.263), Allen Webster, Matt Harvey, Jose Fernandez, Jarrod Parker.
You would expect 20-24 starters to be better than the average since teams are incentivized to keep the less good ones in the minors. It's a pool of great young pitchers that have been deemed ready by their clubs.