There's in the silhouettes a part of mystery, as if the subject was not fully engaged.
I particularly like it because it gives dream and magic to the picture, leaving space for imagination in its reading.
The silhouette leaves the posture and the appearance of the subject in the foreground, by blurring his details. Thus, the movement of the character is purely graphical, and fits in my own aesthetic vision of the composition.
Here again, the black and white strengthens the readability of the image.