I think you're looking at this only with part of a Coach/Trainers role . i.e. Getting the athlete fit.
Their role encapsulates far more than that. It's a pair of eyes seeing what you cannot see in the heat of the battle and because you are looking from the outside in, you can maybe see a solution .
a lot of athletes are just that, but they're not necessarily the greatest thinkers.
It's one thing knowing what to do , but it's another being able to explain to other people exactly that. Man management is a key aspect of any coaching.
This is also why the greatest athletes don't always make the greatest trainers/coaches.
And as far as last Saturday goes, it was basically a case of the blind leading the blind!