Forget the nature of the hit....where was the ball and what was happening at the time. There is a certain code athletes should follow out of a mutual respect. And it goes like this. Pass goes over the middle, receiver jumps, but its out of his grasp, you are a defender within two steps and you blast the guy, not because you are breaking up the play, but because you figure you won't get flagged. CHEAP Shot. You are rushing the QB...ball is gone, but you are just a couple steps away so you try to break the guy in half because you figure you won't get flagged. CHEAP Shot. You are blocking on special teams, the ball is 20 yards away and your man has no chance of getting in on any tackle, but you plant him because you figure you won't get flagged. CHEAP Shot.
Here is a radical idea....when playing pass defense, try to play the ball and the man and then maybe you won't get beaten on the back shoulder fade...oh, and you won't be a cheap shot artist. Make hits that matter. Don't hit guys that are 20 yards away from the play. It's just senseless. Football is brutal enough without dishing out or taking needless abuse. And, trust me, it hurts the hitter as much as the hittee sometimes.
Lastly, tackle. If I had a nickle for every home run hit that turned into a touchdown run when the hit turned out to be a miss I would be a very rich man. Make sure tackles. Frustrate the offense. Make the hits be the late ones delivered by the opposition because you have them all screwed up.
I can't tell where Niles is when EM does his thing, but if the OSU guy is out of the play and Martin hit him just because he figured he would not get flagged. Well, then, it may be legal enough, but it's a cheap shot by a coward. If the same hit is made as part of a wedge play to clear space for a runner, see QC against USC a few years back, well, then its just part of football.