Which members you think don't fit in the group? For any reason, image, voice, personality, etc. They just don't seem to mesh well with the others.
For me, as an example, Haechan from NCT 127 doesn't fit well with the others in terms of voice. It's too high, even child like at times. I think the group would have a more cohesive sound without him or another NCT member in his place.
I do think he works better in DREAM, which in turn I think Mark then becomes the one that doesn't quite fit.
Another example, Yonghee from CIX has a very soft voice and a lot of times, presence. Especially compared to the others that have a more active energy.
Disclaimer> As everything, this is subjective. Also, it's no hate to whoever is mentioned.
