In order to support re-engineering efforts the authors defined a new methodology called QCR (Quantitative, Change sequence and Relation analysis) for software evolution analysis. QCR is defined as an incremental methodology combining three complementary steps of analysis, where the results of each step are used as input to the next. First the Quantitative Analysis (QA) is utilized to give an overview of the entire system and to point out potential architectural insufficiencies within the software system. The results of this first step are taken as input to the further steps. The Change Sequence Analysis (CSA) helps to broaden the knowledge base. It supports the reasoning about the structural weaknesses discovered in the first analysis step. Additionally, CSA provides hints for new testimonies about the architecture of the entire system.