I get your reasoning if comparing Buxton to a Marte - and, yes, Brantley did end up more productive than McCutcheon - but in a sense these examples lend to my point: if Middleton were to green-light exceeding the lux cap, I have trouble seeing it be for a 'you never know'-type proposition, more so than someone like, to use your example, a Carlos Correa.
(Though a decision involving Correa in this instance would leverage the cost of prospects + less $ over the cap against retaining said prospects + extending well into the luxury tax zone... which, given the historical reluctance ownership has shown to exceeding it, may gain points back to the idea trading for, and extending, Buxton. In their minds, at least.)