Thank you for clarifying that the focal point is behind your intended focus point. Yes, I would expect as I have personally experiencing a need for a negative number coming out of FoCal, with one exception...
I am starting to believe from purely anecdotal evidence (I've tested eight lenses on two bodies numerous times in FoCal and added more actuations to my new 5D3 than I'd cared to) that positive and negative AFMA settings, especially within +/- 5 are more of a 'secret sauce' that translates into a formula the camera uses when giving instructions to the USM focus motors within the lenses.
In other words, just because you select a positive AFMA adjustment for a lens (which should technically focus it FURTHER BEHIND your focal point), does not necessarily mean that it will and could actually bring the focus FORWARD/CLOSER to the camera. Here's why I believe this...
Using the AF Consistency test within FoCal, you can see that certain AFMA values deliver far more consistent AF results than other. There will almost always be at least one ore more "outlier" results at certain AFMA settings where the autofocus missed significantly compared to the exposures.
I always take the AFMA result given to me by FoCal from the Fully Automated test, and go into the AF Consistency test. From there, I select the "AFMA Range" option and enter for the minimum, a value 2 or 3 points FORWARD (subtract from the AFMA result given to you by the Full test) up to 2 or 3 points BEHIND (add to the AFMA result), in steps of 1, with 10 exposures at each AFMA increment.
You may be surprised at the results. The POSITIVE numbers you are getting from FoCal may actually yield more CONSISTENT focus results than negative numbers (which we would expect).
Give it a try at least for one of your lenses and see what you get and set the AFMA setting for that lens in your camera to the AFMA setting which gives you the *most consistent* result with a high QoF (Quality of Focus) score.
If your images continue to miss the mark and focus behind your subject, you may seriously want to consider sending your camera body into Canon for them to calibrate it and ensure it is working to spec.