THe bottom line, if nothing else should be a level of personal accountability for one's own stamina and fitness on the fireground.
There are a lot of people I wouldnt trust working with at a going job under any circumstance, due to distinct inability to keep up even under drill conditions.
In dry firefighting work it is just as important as within structure to have good levels of cardiovascular fitness and endurance. Whilst with structure, there is a clean air source in your BA, when it comes to wild fire, there is definate need for both good aerobic and anaerobic fitness.