I took a long look at 517 (the NEF file). Actually, I didn't see anything in the image that was in focus. The wall behind the drummer appears to be closer to being in focus than the drummer's face, but definitely not in focus. My two cents is that you really should investigate whether your 70-200 is back focusing. I own a D800E and with my 24-70 zoom, I have to set the AF Fine Tune to +18 to achieve proper focus. Other lenses have totally different AF settings.
I also looked at the other photos and, again, I just don't see any part of the image on any of them that is truly in focus so that makes it a bit harder to evaluate the problem.
You pointed to two other images where you say the subject is in focus (though it's hard to tell from those small images), but I do see that they were taken with a different lens. That lens may not be exhibiting the same back focus problem as your 70-200 (if indeed, that's what's going on).
One thing I found in moving from my D300 to my D800E was that I really could not hand hold at the same low shutter speeds I was used to due to the increased resolution. With my 24-70, I find I cannot hand hold at anything lower than 1/125th and get perfectly sharp images. I noticed that 517 was shot at 155mm at 1/160th and that VR was turned off as well. That may simply be too slow on the 7100.
And, finally, I'll mention that my shooting style at events is different than yours (we each develop our own style, of course) but I always use the center focus point and focus on the face. I don't mind focusing and recomposing simply because I find it ever so much easier than trying to move the focus point itself. But, that's just my style - not necessarily better than what you've come to prefer. For most of these images it seems that you would not have had to recompose much at all if you used the center focus point on the face.
In any case, I'd really encourage you to get into some good light and see if there's a back focusing problem with your 70-200. If not, at least you will have eliminated one of the variables.