For "quickness" you can work on step ladders etc. The biggest help at the young HS age is strength,balance, and flexibility. A program like P90X that works overall strength and uses Yoga for balance and flexibility is an easy solution that is low cost and doesn't require a lot. Made a huge difference for my oldest in HS. He thought the Yoga really helped his balance and body control. If you are looking to shell out money there are plenty of training places and they all seem to have a good grasp on the needs.
Yoga is Outstanding for all athletes. Kim Johnson has a studio at the PAD over in Woburn. Very reasonable $ . I think $10 for walk - ins.
Works with a lot of Golfers too ( For you dads)