A path of polymer crystallization has recently been proposed by Strobl by which lamellae are first formed in a mesophase, which then convert to the crystal form with a nanoscale granular or blocklike structure. The crystallization temperature dependence of the lamellar thickness was argued to imply a transient mesophase. Here we argue that the granular structure of the lamellae is itself a fingerprint of the transient mesophase into which a lamella originally grows and its conversion to the higher-density stable form. The lower interfacial energy of the mesophases, which cause them to be favored as the initial growing phase, is directly connected to their lower density. The reduction in area at the mesophase-stable transition, being frustrated by the tethering of the stems to the amorphous region, results in the granular structure. We also discuss the effect of the relaxation of the stresses in the amorphous region and importance of hysteresis at the mesophase-to-crystal transition.