I think a mixture is probably the best, because, cynically, I bet people with high social capital could engineer a way to improve their standardized grades as w

I think a mixture is probably the best, because, cynically, I bet people with high social capital could engineer a way to improve their standardized grades as well. By requiring them to cover more bases, it drives their costs up. A ringer is an obvious solution, but there is a lot of room to be "creative." The best way for admissions to pick well is to always remain liquid on metrics. Keep the pool wide; diversify your metrics portfolio.