Phil weighs in, using data and evidence*, here.

Some of his main points: US Department of Education data indicates that the full-time faculty to student ratio has remained almost constant over the past 40 years. (We published a graph showing this in our article at JBE.) So, it’s not true that full-time faculty are being replaced with adjuncts. Rather, over the past 40 years, there has been an explosion in the number of adjuncts (most of which is concentrated at 2-year and for-profit colleges), an explosion in the number of low-level administrative, professional, and other non-faculty staff, and small growth in executive or high-level administrators. While much of this administrative bloat is wasteful, as Phil argues, it’s probably not a giant pot of gold that could be used to “save” adjuncts from exploitation.

E.g., here’s a graph showing some of the trends:

Do read the whole thing.
*In our experience, when you use data and evidence, the other side responds with angry tirades, personal insults, and table-pounding.