Easy to see on video, looks like a very close call in real time. One back starts motion and grabs your attention while another's arm if not his entire body starts while the ball still sits on the ground. Being so tight, it all blends together and leaves you unaware. If you get away with it, well, it's part of the game, if you don't, it's still part of the game. Wilmington is extremely good at it with the timing of it working in their favor. Been that way for a long, long time.
Okay, somebody who watches video...that might make sense. I always assumed they were flagging the back in motion because of the way they stop, start, go back, jump, skip, etc. never thought it was the other wing leaving early. The timing is usually so precise...