I know nothing of the details of the circumstances in Cleveland, only that this is a classic, crosstown rivalry. But let me offer another perspective, in broad terms of purpose and principle, to see if we can shed light on the story from a different (but not the only) angle.
What is the purpose, the utility, of a public high school? Is it not to improve students through classroom education, special interest activities (like band, chorus, drill teams, various clubs, etc.), and competitive opportunities in various sports?
If, by switching schools a student improves his learning potential in a competitive opportunity AND the school he's going to benefits... is this not a good outcome?
Next, is this a situation that is so artificial, so contrived, that it does not reflect real-world conditions, and therefore does not prepare students for life beyond high school? Or does it reflect the real world for which they are being prepared, whether in athletics or business?
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As I stated above, I don't know the circumstances or the people involved. I can imagine ways in which this could be a healthy, win/win situation. I can also imagine circumstances in which it would be very dysfunctional and harmful, both to the individual player and to the community as a precedent.
But I do know the two rivals will meet on the field October 25th, and the outcome of that the boys will decide.