This work compares the simulated degradation produced at the drive-train of a given wind turbine when it is functioning at optimal and sub-optimal operating points. The simulation considers different classes of wind conditions and supposes the use of the same Maximum Power Point Tracking (MPPT) algorithm but calibrated with different feedback gains. The dissipation at the drive-train is modeled using contact mechanics principles, and it is intended for modeling the mechanical fatigue due to changes in wind speed and turbulence. The paper presents the proposed model for the drive-train degradation and the obtained power curves for a simulated variable-speed 2M W (100m rotor diameter) wind turbine, with fixed gear box and horizontal-axis.