I am not clear what is really meant by this. It sounds as if it refers to the distance a car will travel when the fuel runs out.
What seems to me to be a possibility here is that the players we retained from last season have not been able to lift their fitness/capability to suit this level of football as a continuum. The steam has gone and the poor recent results will diminish their confidence and resolve.
It is all very well to concentrate on the owners/board/manager but it is the players who are at the sharp end. It is their stamina and feelings that will dictate how they perform.
In addition, I think that Jim gives away too much in his after-match interview and I am sure that other managers will glean every grain of information from what he gives away.