It is, and the subjective assessment component is a black box. That said, the USDM has many other components that are objective, so it's far from being a subjective measure -- I would argue that the Fed Funds rate, for instance, is determined far more subjectively.

Also, there just isn't a more objective measure of drought out there, let alone a fully objective measure.

Also also, it's unclear to me that this black box is being gamed any harder than most other black boxes in our system. If you want to game agriculture, you game the farm bill.