well i pretty much do the same thing, i play in a bball team and still do weights. i play light basketball at school, and play hard 1-3times a week outside of school, so that counts as my plyo's.

i got bad knees too =p but i guess as long as you get enough rest for your school's games, then you should be fine.

if you feel dead, cut down on plyo's or weights. i'd say plyo's. dont stress yourself

good luck =]