There is a lot of talk of this.
Trent Green got knocked smooth the f*** out while trying to take a linemans knees out. I undertstand that this is how a lesser man would have to hit someone like that successfully, but should it be or is it illegal. If it were a reverse situation, the lineman would have been flagged, and possibly fined for a low blow to a quarter back. In a league in which double standards are argued every week, this seems like an obvious one. Bettis did not think it was cheap, he said that is how Green would have to hit him. Tiki, and Collinsworth disagreed, especially Tiki, echoing the sentiments that if it is illegal in one facet ,it should be across the board.
Let's think for a minute what if the reason it is an illegal hit ,is the harm it could cause the tackler. That is why you don't go diving at someones knees with your head down. See what you hit , hit what you see.
It goes both ways.