In an attempt to add to the current body of research on written corrective feedback (CF), the current study reports on a nine-week intervention, which initially focused on the effect of direct written CF on learners' use of English articles in their writing and then examined the effect of adding metalinguistic explanation to this CF type; and finally, the effect of learners' Language Analytic Ability as an individual difference factor is investigated on language development through CF. To do so, this study used a pretest-treatment-posttest-delayed posttest research design and involved 57 intermediate female Iranian EFL learners aged 15-18 in three intact language classes, randomly assigned to the following groups: direct-only CF, direct CF with metalinguistic explanation, and control group. Initially, the findings demonstrated positive effects for direct written CF provided to learners' writing, though the short-term benefit was more evident and statistically significant. The results also revealed a positive gain pattern through time for learners that received metalinguistic explanation, which supports the provision of such information along with written CF in language classrooms. Finally, learners' language analytic ability was seen to be predictive of short-term and long-term learner gains when received metalinguistic explanation. The findings suggest that metalinguistic explanation provided as part of the feedback to language learners' writing is conducive to a higher level of cognitive engagement and leads to better learning outcomes.