HELP ME LEARN?

i understand all that...but, im not about physically mature adults here....im talking about 10-11 yr olds here...tell me the coaches in your league dont put the biggest fastest kid in the backfield?? and , sure, you teach team defensse, and get him in the backfield, and all that..and most tackles aren head on, theyre ussually from the side, or behind.....but, no matter how much you teach them to tackle legs, hit with your shoulder, drive with your legs, drive thru him, not too him....it dont always happen...and even when you, as a db, lets say, are in a perfect, but statuionary, position, and have to tackle a much larger, MOVING object head on, the law of physics dictates, that you WILL be absorbing the bulk of the energy, thus propelling you somewhat to the arears ....even if you hit him low, and lock your arms, you will still be on your back...hell, dont the teach db s to "take one for the team"? to, just not let the ball carrier get by you? i watched it happen yesterday, all day, and they were PROs....kids in our league, by and large, will make good clean takcles 1/2 the time, the rest, and thats the good ones...and yes we coach them on it ALL the time....but in the heat of the battle, they resort to street ball..stand up and grab...a good running back is gonna put his helmet and shoulder right thru you....or his knees...ive seen piles moved 5yds by big running backs...little kids, no matter how tough, run a risk of injury trying to tackle a larger, strong, fast, athletic running back, if we dont regulate it, and would you run the risk of even ONE kid getting hurt so you could use a big running back to win a game?....i played mlb in high school...i weighed 160 lbs...i had to make a tackle on a 220 fullback on a draw play at the goal line...he had a full head of steam, we were in a prevent, up by 2 tds....i nailed him hard as i could and he fell short.....they had to scrape me out of the mucd....two 2yds back from where i hit him....i woke up the next day with a major headace....didnt remember till that nite that i had even been IN a football game....I had no clue...I had played the rest of the game with my teammates telling me the plays, and they had to drive me home........same thing happened to me when i played for the Falcons on a punt...i came down and nailed the guy....i woke up 2 days later at work with my face in my soup at lunch...with no idea of the past 36 hours...explains alot, i know...the worst part is,noone noticed the difference..hahaha....point here being...we arent putting kids at risk by using the biggest, fastest kids in the backfield, no matter how tempted we are....thats not what youth football is about.....