L2 learner's achievement is closely related with teaching efficiency and educational policy. The use of single scale form (rankings) of measurement as well as subjective judgment have its underlying danger. In addition, it largely neglects the fuzzy characteristics of human concept. The drawbacks above can be properly treated if we utilize the fuzzy statistical analysis. The focus here is on how one might exhibit the effects of differences in diversified backgrounds of students on the resulting achievement. By means of the fuzzy measurement, soft computing and fuzzy statistical analysis, we attempt to go one step further into revealing properly the efficiency of teaching and the proper use of teaching materials.