Momentum decoupling arises when small momentum transfer processes dominate the electron-phonon scattering and implies that anisotropies in superconductivity are driven by the anisotropies of the density of states. Considering an isotropic s-wave interaction in the momentum decoupling regime we give a natural simultaneous explanation to various aspects of ARPES and tunnel experiments on Bi_2Sr_2CaCu_2O_8, including the correlation of gap magnitude and visibility of the dip above the gap, the

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... ncement of anisotropy with temperature, the presence of gap minima away from the Γ-X direction and a gap maximum in the Γ-X direction, the similarity of tunnel and ARPES spectra in the Γ-M̅ direction and the asymmetry in the SIN tunnel spectra where the dip structure is present only at negative sample bias.