The strain of twisting the whole body to play the shot on the left of the pony shows!
The most common shots in polo are the offside forehand and backhand played on the right of the horse. Less common but very effective are the nearside forehand and backhand shots played on the left side of the pony. The difficulty is in the twisting of the entire body to play the shot.
The players face in this illustration shows the effort involved in the nearside backhand shot.
All players now play right handed even if they are natural left handers since a rule change in 1974. Pre 1974 you could play left handed.
And the player strikes the ball with the side of the mallet not the end as it’s polo not croquet!