Not unless they are a key player. If your individual stats are bellow the squad average than the only part you may affect is the POINTS or CAPTURE lines. They are totals. All the other lines are averages.
If you are well bellow the average and also don't play much than they are better off without you.
The truth is there are a lot of vaireables involved.
For instance: The squad score will be better if a fellow that can't bomb doesn't. If he sticks to fighters and is above the squad average in them, he is still an asset and will be missed if he leaves. His ranking will suk, but the squads is not effected as much by not doing somthing as it is by how well you do it.
And if it's a large squad than you may still not be missed from a scoring stand-point.