I have some players whose average form is different by about 1, but this is with a limited number of data points. I need to be patient and collect more before drawing any conclusions.
My spreadsheet also breaks it down by type of game (Leauge, CL, Cup). It appears as if some players perform 1-2 form points better in one type of game over the others. This is not just due to lower skill levels in league games. Some prefer cup or CL. Although this is more easily observed because the game does show us the last several forms broken into game type.