Body parts are nice wrote:
What's the importance of strong academics and extracurriculars?
I think it shows a couple of things:
1.) It puts "good kids" on the team. By "good kids," I mean those, usually, with morals & ethics that will contribute to the team. (I would rather have a bad team with good kids on it, than a good team with a-holes on it.) And, those same kids might--just might--influence the others on the team to raise their academic "game" too.
2.) While not necessarily completely true, those with "drive" (in this case academics & extracurriculars) will have the motivation to participate (including summer running & 6 days a week of practice).
3.) You may--in fact--find a "diamond in the rough" amongst those "new" students (with strong academics & extracurriculars) who choose to partipate.
Also, a place to find new runners might be band. Laugh as you may, they also show dedication (to their instruments) that might translate to the XC course or track.