Different Type of Grouping?

So far in my Education career, reading levels have been a question of mine. How to assess children? How to determine what books they can read on their own, and which books fit into their "zone of proximal development," or books that they can read with some help? After reading Glasswell and Ford's article Leveled Books, some of these issues are talked about. Too much emphasis is put on assessing reading level and too little is put on what the students actually need. In one of the examples I read, a teacher has a group of three students who are all reading below grade level. They are put in the same reading group and instructed the same. After doing a miscue analysis, which is explained in detail in chapter 6 of Kidwatching, the teacher notices something. One of the students struggle in decoding, one struggles with comprehension, and one student struggles with predicting. Should these students be put in the same group? I believe that it would be more beneficial for the students is they are grouped according to what specific instruction they are struggling with. If Stacey, John, and Mike all struggle with comprehension, but they are reading at different levels they will still benefit from a mini lesson on comprehension even though they are reading different books from one another. If instruction is aimed at building up strategies that they need assistance with, regardless of their reading level, each students needs are met.