And when the border patrol is driving these illegals back across the border at a regular border crossing and goes through all the paperwork at the other end and possible refusal by the Mexicans to allow entry, what is to keep 10-20 times as many illegals from entering while the border guards are gone? They dont release them because they are led by stupid beauracrats. They release them because they dont have any where to store them and no one to return them to the country of origin assuming that country would take them back.
That's why you build a border fence - to keep people out in the first place and to keep them from coming back once deported.
But making excuses for why things are the way they are isn't going to get anything done. It's just going to give cover the the cowards in washington who refuse to do their job.