What makes Memphis such a great defensive team?

[heyPlayer]

It seems like once they get warmed up defensively, they just absolutely lock down the most talented "run and gun" type of teams. They do a bit poorly to a skilled half court offensive team, but against super scoring teams, they just absolutely lock down and take over at times.

Why is that? Do they work really hard on defensive chemistry off the court? Cause they don't exactly have the most length or athleticism.