This study aims to evaluate and investigate the influence of teaching techniques on the performance of English as Foreign Language (EFL) teachers by evaluating the techniques' effectiveness and actual implementation, as well as to examine the role of teachers in influencing the effectiveness of in-service training courses. A total of 798 questionnaires have been distributed to teacher-respondents. Qualitative and quantitative approaches have been adapted to aid in the evaluation. The findings of the study, taking into account the teaching techniques' effectiveness in the in-service training courses and their impact on EFL teachers' performance, have revealed that EFL teachers' in-service training courses did not emphasize good and effective teaching technique.