  Exclusive semileptonic $b$ hadron decays ($b \to u \ell \nu$) serve as a
sandbox for probing strong and electroweak interactions and for extracting the
CKM element $V_{ub}$. Instead, this work investigates their underexplored
potential to reveal new short-distance physics. Utilizing SMEFT as a conduit to
chart territory beyond the SM, we demonstrate that substantive new physics
contributions in $b \to u \ell \nu$ are necessarily linked to correlated
effects in rare neutral-current $b$ decays, neutral $B$ meson mixing or
high-mass Drell-Yan tails. We find that measurements of the latter processes
strongly restrict the allowed deviations in the former. A complete set of
tree-level mediators, originating from a perturbative ultraviolet model and
matching at dimension 6, is thoroughly explored to support this assertion. As a
showcase application, we examine the feasibility of a new physics
interpretation of the recent tension in exclusive $|V_{ub}|$ extraction from $B
\to V \ell \nu$ where $V=(\rho,\omega)$.
