Soyeon is carrying gidle on her back

well to be honest it's the case since their debut

and it will look even more like this without soojin

Quote from Minlix15

^ this

Soojin rlly balanced the group

well they kinda balance each other in stage presence

Soyeon is an aggressive performer, she'll try to appear as strong and impress on stage, who tend to over react with her facial expression

while soojin is more a seductive performer, her expression will be natural and she'll try to seduce the public

so both performer in the group were kinda balancing the group

but without soojin it will just look like soyeon and the rest , and soyeon will took over the stage