I've been sent a demo of someone who is possibly walling.
Demo: https://drive.google.com/file/d/0B023F_ZbP0xGTkJLbm5aM0p2SWs/view?usp=sharingFrom memory the few spots where he made it obvious on this were when he was heading towards the docs and up the stairs, and also looking down into the outdoor area with the trucks.