Proper football, eh?
I say we take an NFL team, any of them, you guys pick one.
Put them in "proper football" (soccer) gear and make them kick that ball around against the best "proper football" team.
They'll loose, likely badly. 
Take a "proper football" team, your best, ladies, and dress them out in "Real Football" gear. Make them play any  "Real Football" team from the NFL. Hell, make them play any  Div 1 college team in the top 100.
They (the "proper footballers") will not only loose, many of them will be in the ER. Some wheelchair bound for life. A few will be in the morgue.
That's the difference between your  football and our  football.