I read in a pedal review that if you remove the back row of pins from your pedals you don't get gashed as is that row that does the damage
no idea if this is correct, the pedals (cant remember their name now) were meant to be the next big thing and you could screw in different sized pins etc
but i do remember getting a bear trap stuck right into my shin once in the 80's and it was indeed at an angle, it may be to do with the way the pedal rotates as it hits your shin the top will push away (least resistance) but that means the bottom will be forced into the leg ?
anyway... back on topic, the football shin pads are a reasonable idea !