Similar situation for my son. He is starting LB, LS, and backup QB. Not a huge fan of him playing LB but it is where our staff thinks he helps team most and has played the position since 3rd or 4th week of junior season. If this helps at all, last injury for my son was separated shoulder while he was playing some TE soph season. Injuries occur at every position but OL and DL do get a little beat up just because they are guaranteed contact on almost every play. They also, in my experience, incur more abuse to the hands because they are constantly using their hands to engage opponent. QB's can also take a fair amount of punishment depending on offensive system and ability of OL to protect.