I'm a bit slow on the uptake here. That bloke who got decked was planning on jumping on Sandi and punching the ball away. Probably planning to use Sandi as a step ladder.
Look, if other clubs want to do that, lets put Ballantyne as ruckman, and have Sandi go 3rd man up. Use Subes and De Boer to make sure Sandi gets a clean run at it. I reckon Sandi's knees would be quite painful as they crashed into your back or shoulder. In no time at all, the AFL would discover that, yes, there is a problem with this 3rd man up malarkey, and it would be fixed.