Most of my photography has been of relatively stationary subjects, where I just use single-servo AF and either focus & recompose or move the single focus point to where in the frame I want the subject, or largely-individual sports like triathlon. But I've struggled getting sharp shots in team sports photography with a large number of moving people in frame.
If I try using continuous autofocus, it often focuses on the wrong subject or the background or seemingly nothing at all. If I try falling back on the techniques that work in other contexts, I usually just can't get the shot off at the right time.
I don't really understand the different autofocus options on my camera. I was mostly using what it calls "3D", but I also briefly tried "group-area". I don't really understand how group-area differs from d9 or even 3D. And my camera's manual doesn't clear things up for me. I spent a little while in manual autofocus with a fairly closed aperture, by using autofocus and then switching to manual and leaving it untouched; but this only worked when play stayed roughly the same distance from the camera for a while, so didn't really scale well.
Separate from the focus question, I spent the afternoon shooting at 1/1600. I'm not completely sure if this is fast enough, and maybe some of the blur in my photos is actually better explained by camera shake (shooting at 200 mm on a 1.5x crop sensor) or movement of the subjects. I suspect it's probably not relevant, but I thought I'd mention it just in case.
What's the best advice for how to get sharp shots in team sports photography?
(Included photo is a SOOC jpeg of a set play on the opposite side of the field from where I was...a situation that minimised my chance of focus problems.)
So, ideally I'd like to keep the aperture wide precisely because I want the low depth-of-field. As it happens my lens isn't a very fast one (55–200 mm f/4.0–5.6), and a fair few of my photos were stopped down to around f/6–8 anyway, especially the ones where I had switched to manual, but the reason I was asking for assistance on how to nail the focus is to help get the sharpest subject I can and be able to keep a nice soft background.
With max shutter speed (looks to be 1/8000 on your D7500) try following your subject while shooting (a.k.a. panning), and you should get nice motion blur on the background like this: https://static.wixstatic.com/media/4af1e0_0c4400474dff4f94a8873a2d235b1139~mv2.jpg/v1/fill/w_1280,h_720,al_c,q_90/4af1e0_0c4400474dff4f94a8873a2d235b1139~mv2.webp
https://digital-photography-school.com/6-tips-master-panning-photography/
Also to keep in mind that many consumer grade lenses get soft at their max zoom levels.