Hi,
Welcome.
I use this lens with a D7000 and get great results.
You need decent light or higher shutter speeds to get the best results.
I found my images improved massively when I started using a monopod/tripod. Most of the early issues I had with sharpness were down to me.
Why not post up some of your images and exif data and we can have a look.
I mainly shoot at f8, and try to keep the shutter speed above 1/250. Iso varies, but I have used 1600 regularly, and fine as high as 3200. Your 7200 will be better than the 7000 at higher iso.