The problem of increased energy usage in refiners over the working life of a refining assembly is mitigated by the use of a refiner plate segment having a refiner side and a back side distally disposed from the refiner side, refiner bars engaged to a substrate of the refiner side, wherein the refiner bars have a refiner bar height, and wherein adjacent refiner bars and the substrate define grooves between the adjacent bars, and protrusions disposed in the grooves, wherein the protrusions have a protrusion height, wherein the protrusion height is 30% or less of the refiner bar height.