Your table tennis Mechanics of the arm-swing with a quiet shoulder is the secret of controlling blade angle to eliminate unforced errors.
Your upper arm is attached to the shoulder in a round socket, therefore it is impossible to (swing straight) back or forward; when you swing your elbow to shoulder (upper arm) forward your blade angle will automatically open the blade (in proportion to length of the upper arm travels forward to and through the ball contact. This is the exact opposite of what's best.
Among coaches, there has always been a controversy about the forehand loop technique.
Should the stroke for an exact straight line or should it be somewhat circular? From watching many, many, MANY top players, it is clear to me that the motion should be somewhat circular. I have chosen this short video clip to show you Rye Seung Min's forehand from multiple angles. Go to settings, and watch this youtube video using google chrome on the slowest slow motion.
When hitting backhands, many table tennis players do a great job hitting to different locations. Because they are able to bend at the wrist, these players are easily able to contact the inside of the ball, the back of the ball, and the outside of the ball in order to hit to different locations.