What caught my eye in this NYT article about the city replacing grass playing fields with sportsturf was the fact that the first paragraph refers to a 13 year-old kid throwing a curveball.
While Little League says that studies regarding the effect of throwing the curve are inconclusive, most respectable pitching instructors recommend that a kid should be at least fourteen before he starts throwing true curve balls due to the fact that soft growth plates of kids can be easily damaged.
