In Summary: I think you should swap out Player A and another outside hitter with the libero rathar than your middles. Statistically you are losing far more points on their returns than your middles, that could be because the middles don't get the number of returns to pass since they are rotated out (um, yea. That IS the reason), but you also would be saving Player A's energy for what she is focused on - hitting the ball. If that is her main contribution (and statistically that's what I can see) then why not have her focused on that? (What a great idea except for the part where there is nobody else that passes consentingly better than her in the back row). She is bleeding as many or more points from return errors than she is generating from her attacks. I would also take a look at how Player B is serving and see if she can find the groove again. (What a novel idea! See, here I was thinking we should just keep Player B in her slump)
Umm, I'm sorry but substituting the libero( a back row defensive specialist) with an outside hitter means one of the middles will have to play in the back row. Believe me, their states would be MUCH worse than Player A's. I know, because I watch them pass at every single practice and game we've had this year. And yes, the middles' passing states look better because they don't have serve receive states to muddy up the data. If they did play back row...the states would negatively correlate to show that. Thanks for the data, but I've taken statics too. I think I can safely interpret the data for myself and make my own decisions, probably better ones. Have YOU ever played volleyball Mr. Concerned Parent? I think not.
Oh, and that middle hitter Dad wants to play all the way around the court? Yea, that's his daughter.