I wonder what the correct answer in a refs exam would be to this photo? Evans has both feet off ground, studs flying, missed the ball, could break the mans ankle. Shelvey is in an acceptable, non violent stance, but clearly mis times tackle, and could break the mans ankle. Ain't easy being a ref, ent?
FS, in fairness the photo doesn't tell the complete picture. Evans got to the ball (which was situated just in front both of his feet as shown) a split second before Shelvey, who then knocked it away with his right heel, sending the ball off to the side. A frame later and Shelvey too had left his feet, with the left leg following up from the side as both players rotated slightly clockwise.
But the picture is clear in showing that Evans is guilty of the same offense for which Shelvey was punished... a lunge
"at an opponent when challenging for the ball from the front, from the side or from behind using one or both legs, with excessive force and endangering the safety of an opponent", as defined by Law 12(1). How a ref can dismiss one player on a 50-50 challenge and not so much as caution the other is what beggars belief.