Simply put, he can play facing the basket and has a decent jumper 16 to18 ft out
That's how he spreads
I found this so odd that I went to check the numbers.
Willie Cauley-Stein shot .069 of his attempts from 16ft out to the 3pt line (and .065 from 10-16ft). That's less than 7%.
He made 35.3% of those shots (35.4% from 10-16ft, and 31% from 3ft to 10ft, so he's equally horrid at everything that isn't a lay-up or a dunk).
That means that last season he shot 28 two-pointers from beyond 16ft. And he made 10 of them.
That's one shot every 8 games. A player isn't spreading much by hitting a midrange every two weeks.
(even if you every shot from 10ft out - he only made 19 of them)
That line-up could contend for worst offense in the NBA. That combination of lack of playmaking, dribble-penetration, passing and shooting would be absolutely deadly.