This paper presents a mechanical framework for understanding giant planet structure through core-shell decoupling, wherein the gravitationally bound relationship with the host star operates primarily through the planetary core rather than the visible atmospheric envelope. Analysis of Uranus's extreme axial tilt (98°), Jupiter's persistent atmospheric features, and magnetic eld-rotation axis osets across outer solar system bodies reveals that consensus`gas giant' and `ice giant' models contain fundamental mechanical contradictions. The Webb Mechanical Metric (WMM) framework resolves these contradictions by establishing that giant planets possess massive, dense coressignicantly larger than standard models predict with outer layers (gas or ice) mechanically decoupled and capable of independent rotation. This architecture explains observed phenomena including Uranus's rotational stability despite polar spin, Jupiter's centuries-stable banding patterns, and the 59° oset between Uranus's magnetic eld axis and rotational axis. The framework generates testable predictions distinguishing it from consensus interior models.