Clearly, there have been differences in performances between players of the same position, same age and almost same visual quality, and there must be something that govern this. What makes it even more noticeable is when the weaker players perform better, not only in the short term, but in the long term as well, in the same position compared to the visually higher quality ones. There might be something like form which changes more frequently (short term effect), but there is good possibility of less dynamic (more fixed) hidden factors assigned to players which what seperates a good player from a bad one.