Considerable efforts have been recently devoted to the task of small-scale modeling of crystal plasticity at a reasonable computational cost. A fully detailed description of plastic flows in crystals is possible only by molecular dynamics (MD) approaches, which accurately represent micromechanisms of plastic response while relying minimally on phenomenology. However, in most applications, such an approach is prohibitively computationally expensive, even if one deals with ultrashort timescales and ultrasmall samples. The discrete dislocation dynamics (DDD) approach was created to overcome the short-scale focus of atomistic methods and inform various classical continuum models. However, the DDD models contain many parameters since the processes of dislocation nucleation, interaction with defects, self-locking, climbing, etc., have to be prescribed phenomenologically through specific local rules coming from independent phenomenological constructs. Other major challenges in the DDD framework include accounting for large plastic distortions and incorporating the effects of anisotropic elasticity. To achieve a compromise between more and less coarse-grained models, we adopt a novel approach known as the mesoscopic tensorial model (MTM). It represents a crystal as a collection of homogeneously deforming elastic elements whose nonlinear elastic response is governed by globally periodic potential defined in the space of metric tensors. The potential is designed to respect the geometrically nonlinear kinematics of the lattice. From the perspective of the ensuing Landau-type model, the elastic potential has an infinite number of equivalent energy wells, and therefore plastically deformed crystals can be viewed as coherent mixtures of equivalent ‘phases’. In this work, we apply the MTM approach to the study of microstructure formation in crystals during plastic deformation. These microstructures are composed of randomly rotated patches of the unstressed lattice. We will show that while such ’patches’ disguise themselves as an elastically neutral rotation, behind it is an inherently dissipative, dislocation-mediated process. We then investigate dislocation core properties along these grain boundaries. Finally, we compare our results with MS simulations.