When Charlie Rader is sparring, he has his back to the cage, one of the trainers tells him to get his back off the cage & he doesn't do it.
Later, Charlie has his back to the cage and Brock is wearing pads. Brock is throwing some low intensity punches at Charlie as Charlie leans back against the cage.
I think, Charlie might have a bad habit of lying on the cage and they were trying to get him to break the habit.
Another thing he might have a bad habit of doing. When he's in the clinch, he only throws 1 or 2 punches, then stops. There were instances there where he wasn't really in danger of being taken down and he just stood there because he was paralyzed and worried about the TD.
I think Charlie knew his head wasn't in the right place and didn't feel properly prepared and he just wanted out of there.
Brock can tell him to get off the cage, but if he already has a habit of lying on the cage and being content to be there, it won't make a difference.