To investigate the role of shocks in the generation of gamma-ray flaring in blazars and to identify the physical conditions in the radio jet outflows during flares, we monitored the total flux density and linear polarization of a sample of radio-and-gamma-ray-bright blazars at 14.5, 8, and 4.8 GHz at the UMRAO during cycles 2-4; we are comparing the observed light curves with simulations from radiative transfer calculations allowing for shock propagation at unrestricted orientation to the flow direction. We find that retarded time effects do not play a major role in determining the outburst shapes compared to blending. Using PKS 0420-01, we illustrate a method for separating blended flares that uses model light curves for both total flux density and polarization. This work was supported in part by NASA Fermi grants.