Update:
Apparently the US National MX series is not the only championship suddenly affected by injury. Today MXGP points leader Max Nagl crashed in his qualifing race and broke his ankle. He will not be able to race his home event in Germany tomorrow. This throws the MXGP series wide open.
These are the conditions that can lead to big changes in a championship series. This picture is from the MXGP in Italy last week. Check the short video below this picture to see how chages can happen.
