Not sure Leyland being diminutive is the issue, it was his technique. If a bigger guy is running at you, your task is to try to grab his knees/ankles and hope someone helps you out up top. What you don't do is jump into that big man's chest or you will end up in your looking daft.
He wasn't the only one by the way, the number of times we actually got to French in particular and just got bumped off was ridiculous. If he does you with footwork or a bit of skill, fine, but he's not so strong that our players should be brushed off.