If the test results agree with actually shooting results, it would appear that your camera needs to be adjusted. Any Nikon authorized service center can do it quickly.
Last spring, while shooting an event all my wide angle lenses suddenly focused poorly while all those over 60mm were as good as ever. I was heading back to the States in a few days so arranged for Precision Services in Sacramento to look at it. When done it was done, no parts were needed, just adjustment and it was returned in like new condition. I sure would like to know who they clean the exterior to look so good. The well used D7000, when unwrapped could not be told from new. No charge.
A consistent -20 focus bias indicates your needs similar adjustments.
Stan
St Petersburg Russia

Visit my Nikonians gallery.