If theres is anything that has improved during durant trade, it would be there defense. durant is a shooter but he is good enough as a pf and he is tall enough to defend big men as kerr has stated to start green as center and durant is even taller than green.
Durant really has a good height but he is not designed to take the Power Forward position based on his actual playing style.
Kerr will likely not to put this guy on that position if they are on defense since it's not Durant's specialty.