The Girl who Loved Tom Gordon.

Nine-year-old Trisha McFarland strays from the path while she and her recently divorced mother and brother take a hike along a branch of the Appalachian Trail. Lost for days, wandering farther and farther astray, Trisha has only her portable radio for comfort. A huge fan of Tom Gordon, a Boston Red Sox relief pitcher, she listens to baseball games and fantasizes that her hero will save her. Nature isn't her only adversary, though - something dangerous may be tracking Trisha through the dark woods. ([source][1])

[1]: www.stephenking.com/library/novel/girl_who_loved_tom_gordon_the.html