He is a GREAT defender and I mean GREAt.
When healthy, he ius a smart player booth ways , and with a guy like Jimmy Butler, they would be SICK
To be honest when I watch deng I would say his defense is just good at best. He has the length that allows him to better guard other forwards, but in terms of quickness and 1v1 he's no gary payton. His jumper his hot and cold, well that explains his whole offensive game. He is a great role player, but his often overrated by people.