The outsourcing of logistics services has become an increasingly relevant practice for trading companies as it significantly improves their costs and productivity. However, service providers often fail to maintain standards that may guarantee adequate customer satisfaction levels. This is reflected in the logistics service quality issues faced by many Latin–American medium-sized logistics service providers. Within this context, the present research study aims to find a model that can diagnose the causes of these service quality issues in a timely manner. The proposed model uses operational mapping tools, simple information gathering, correlations, and control charts. In fact, the authors’ motivation for this study lies in conducting more complete assessments and reducing undiagnosed spaces along with increasing knowledge in the use of diagnostic tools as a whole within the logistics services sector.