Dk is exactly what everyone who evaluated him thought he was--a very straightline fast and huge wr. Metcalf will excel on go routes, skinny posts, slants. Anything that requires change of direction will not be his game.
Part of what makes him great makes him limited. His size limits his ability to drop his hips and explode in and out of breaks--which limits his lateral movement.
Metcalf is a complementary receiver. He is a guy you have to give over the top help against due to his speed but you can play him with inside leverage and essentially remove everything but the deep ball from his route tree. Especially when you have a Ramsay who does not allow Metcalf to box him out from the ball.
Good player but limited and tremendously overrated.