“Why has Yale not been able to muscle its way into becoming an engineering powerhouse, by spending down its endowment?”
Yes, execution matters.
Yale has not muscled its business school into the top along the M7 despite them being a much richer university either. They built a new facility. They re-branded. They even went as far a poaching the dean of Booth.
Execution matters. UChicago can still fail at execution too - that is a bigger risk than the endowment. But so far, the changes have been thoughtful, right sized, and targeted (IME, Business Econ, UCareersIn, TO). And the execution has so far been net positive or neutral.