5D Mark iii Autofocus question

[jeffabbyben]

I have read the manual and I am not understanding how the accel/decel tracking and the Autofocus point auto switching work differently. It seems like to improve the accel/decel tracking it could only be done by increasing the sensitivity of the autofocus points (which is a different parameter). I went to a track meet and tried to image some pole vaulting and had mixed success with different settings. Can someone explain how the accel/decel tracking actually works differerent from the autofocus switching