There was actually a study done by Todd Lu at UCLA that studies this exact thing at https://scaleatucla.weebly.com and it covers the entirely of the UC system's change from 1993 to 2014 as it shifted to administration-led. Most significantly it shows the downgrading of teaching to increasingly done by adjuncts.
[0] https://scaleatucla.weebly.com/ucla-senior-management-growth...