Well, they were sliding after the IND, SAS games, the latter of which Metu was in the rotation but was not starting. In the OKC game he was starting, and Bagley followed suit to be in the rotation after that. This was around the time that the rumblings were coming out that his job might be in jeopardy due to the slide.
Luke saw his biggest issue as rebounding, so he made the adjustment. I honestly think he might have been safer had he just stayed the course.