He's a great second striker.  Hanging out around the edge of the 18 with a target striker in the box.  Can really finish.  So yes, he should've been pushed up front with DCL.  For certainly, playing behind him as a F9 maybe.
He can cross the ball, too, and can play a bit out wide with the threat of cross or cutting inside, but who the heck can play out there with Martina?  It's painfully obvious we are asking the backs to provide the width in attack, and Cuco won't go forward even when there is space.  It's brutal.  Back stays wide, attacker cuts inside.  This isn't that complicated.
Think we'll see JonJoe and Baines Sunday and it'll be an improvement for sure.  Those guys can play wide, allow for our left and right attackers to play as the inside forwards Koeman wants them to be.  Siggy on the inside and we should be good.
But it still all starts with a single striker up front.  DCL isn't getting it done.