I describe a method for analyzing pop-rock musical styles by extracting chord patterns based on their structural roles in relation to melody and lyrics. Previous work applied models such as n-grams, treating chords as equally chopped fragments without considering their functions with respect to musical structures like phrases. In this paper I focus on chord patterns at the end of segments as suggested in lyrics and melody. I study punctuation marks in lyrics and apply established melodic segmentation methods to retrieve segmental structure of songs, and extract two-chord patterns at the end of retrieved segments. I also examine the manner in which lyric punctuation coincides with melodic boundaries. In the experiment consisting of 101 pop-rock songs, it is observed that 68% of extracted patterns differed from those defined as standard cadences in Western classical music. Focusing on those non-standard patterns seems beneficial for differentiating composition styles among pop-rock bands.