Sorry I'm slow getting back to you. I've been working every day. I appreciate the compliment, but will have to respectfully disagree with some of what you are saying.
First, a monopod is simply not practical for many of these shots. I frequently shoot off of a ladder to get over softball and baseball fences as well as tennis. If I was having trouble with focus or holding a camera steady then a monopod would undoubtedly be practical. Otherwise it's just extra weight to drag around.
Second I don't use Topez, or any other sharpening or denoise program. Since the corporate office took over doing page layout for all 23 papers in the corporation they do not want photos sharpened or denoised as for some unknown reason they are applying the same amount of sharpening and denoise to each photo that goes in print, so what you see is the sharpness and noise that was there when the photo was taken.
Third, I will continue to use an extender. My boss asked me to take photos of baseball games from the same location I have been shooting softball from, which is in right center field behind the fence. I need at least 800mm and in some fields 1120 to shoot from there. Yes, there might be a small amount of image degredation, but it is still better image quality using the Nikon 400 f2.8 with a 2x extender than my old Sigma Sport 150-600 without one and it gives far more reach. When a sports editor says to shoot from the outfield you find a way to shoot from the outfield.
Finally, I went back and looked at the Exif data from all 10 of those photos I found one photo that was not shot wide open and it was the only one where the ISO appears to be a little high. The reason for that is pretty simple. There are several buttons on the 400 lens that are near where I hold the lens and if I accidently hit one it changes the fstop, which is exactly why I do not shoot in manual. Shooting with auto ISO adjusts so that even if I accidently do change the fstop while shooting I will still have properly exposed photos. I think you do a great job with your photos. I also think that the photos that my sports editor and publisher expect are very different from what Max Prep Sports wants, so what works for one of us may not work for the other.