[MattMattMatt]

This is a simplification. Khan's mentality is a particular weakness for him because of his physical limitations (i.e. chin). Having a fighters mentality is excellent for someone with the punch resistance to allow them to impose their will on their opponent with a relatively low risk of catastrophic results. Khan can't do that, the risk is too high (hence the sporadic KO losses), he needs a mature attitude to temper his fighters instincts.

In this sense, Hunter is right, Khan's mentality was exposed so that his fighter's mentality would kick in, overriding the measured boxer's approach (which Khan has shown), and put him in a position where his physical limitations were much more likely to be exposed.