DISC measures four communication styles — Dominance, Influence, Steadiness, Conscientiousness. It was never built to measure sales performance. SalesFit measures the 80 sales-specific dimensions that predict closing.
DISC tells you how someone communicates. SalesFit tells you whether they will close deals. They measure entirely different things.
SalesFit's underlying behavioral wiring layer (Competitive Wiring Index — Hunter, Connector, Anchor, Analyst) is independent of and more predictive than DISC for sales-specific outcomes.