We present the results on SiCN-(La,Sr)MnO3 (LSMO) composites correlating the observed large piezoresistance behavior with the microstructural features and defect chemistry. Scanning electron microscopy characterization revealed the presence of self-assembled periodic microvalleys in the microstructure with width of 1-5 mu m and depth of 600-1000 nm. The microvalleys act as stress concentration points providing change in volume with applied stress. High resolution transmission electron microscopy measurements conducted on composites showed that LSMO grains consist of SiCN phase but no inclusions were observed.