It's not about being convincing
(in this case), it's about bad composition. The entire visual balance of that image is strongly weighted to screen right, creating an off-balance sense. And the intersection of the hand and the Enterprise's saucer is smack dab in the center of the screen and set right on top of the planet's horizon. The result is an unbalanced visual jumble. The rules of composition have been discarded and a number of cluttered element are concentrated in the middle of the image, resulting in a lack of focus.
It's poor quality work. If you don't believe me, believe Maurice; he does this stuff for a living.