The outside defensive efficiency is not the same as his outside defense skill: it depends on other things as well (similarly for "inside defensive efficiency").
My impression is that it is more match-up based... So the principle weight is how the SF (in this example) matches up against the other SF. There is a modifier based on the inside and outside offensive and defensive "efficiency". However, the main component that determines if a shot goes in is the individual match-up.
Anyhow, that's just my impression.
Run of the Mill Canadian Manager