As to the origins of the possible perp, she was also really active in basketball. Another thing she did in the days leading up to her disappearance. Could be a coach, teammate's parent, etc. A theory I have made in the past is it could be someone with knowledge of her lost basketball game. Maybe they offered to give her lessons or practice with her.
I think a youth basketball connection is also viable. As for the designated purpose / arranged meeting possibility, it might be good to examine how she may of communciated with a possible / probable predator.
Asha was sheltered, but by no means isolated. Pocket cell phones were available, but I believe land line phones were still the main phone. I doubt Asha's parents would have been among the trend setting and gotten Asha cell phone ahead of her peers. Likewise, her phone usage would probably have been monitored in at least a general sense.
The a bove would seem to leave two forms of possible communication:
A. Olde fashioned face to face talk and interaction
B. Perpetrator provides her a secret cell phone.
Of these two possibilities, I think "A" is far more likely as pocket cell phones were still somewhat novelties back then for pre teens (and even for a certain number of adults). I dont think a pre teen being gifted a "secret" cell phone would stay secret for very long.
Option "A" in Asha's experience would seem to be limited to school, extended family and inlaws, church, and as you pointed out, a basket ball team.