can you game this system by moving to a worse area? If you're rich and give your child all the support they need they're almost bound to be in the top 10%.
Though that'd be a likely outcome, it's also good in itself. If you have rich, well educated people moving to impoverished zip codes/shitty school districts to get their kids a leg up, that improves the tax base for those districts and, more importantly, makes a well-educated constituency active in maintaining accountability for that school district.
I’ve known of folks who moved out of frisco and Plano suburbs to prospect when it was up and coming to spare their kids of the “Asian competition onslaught” in frisco and Plano schools. Not sure whether true or how it worked out. But yes, people do try to game it somewhat. I’m unsure how successful they are in the long run.