My understanding is that in dynamic area AF the camera uses a predictive focus to help it pick up your subject each time the mirror is down. I have had many bird-in-flight sequences were I started firing before focus is achieved and the camera usually locks on by the 3 shot or so.
I also see the same issue as you are describing in the OP. Sometimes the “predictive” AF is not so accurate so the camera must find the subject again and sometimes it misses for a shot or two.
A custom setting you may want to experiment with at the next soccer game is Focus Tracking with Lock On. This setting tells the camera how long to wait after losing your subject before looking for a new subject. Try setting it to a longer setting and see if it helps.
I am not so sure about using the 3D focus setting. I think it is best suited for slower moving human (it uses face recognition) subjects. A fast moving sport with a lot of people getting bunched together may cause problems. On the other hand it is worth a try.