Player ratings during matches

You have all seen it. In some matches a player has a stinker (gets a 5 rating) and in others he plays well and gets a 9. If a bunch of your players get a 5 you will probably lose, if a bunch get a 9 you will probably win.

Here is a case in point from a game today, a stronger team beaten by a weaker team, with the stronger team having many 5 ratings.
https://www.virtualmanager.com/new_matches/85112066/summary

So here are the questions.

1. What precisely dictates whether a player plays well in a game and does this lead to say a 5 rating (if poor) and say a 9 rating (if good)?

2. How much of this rating score is random (if any) and independent of the match opposition, and how much is a consequence of how "the programme" analyses the strengths and weaknesses of the two teams and their respective tactics?

3. Do the generated player ratings partly or wholly dictate the game outcome, or like the visualisation, are they a "retro-fit" unrelated to how the game outcome is determined?

Does anybody know?
I've been playing this game many years and I still scratch my head about this.

Thank you, Rolf

It would be interesting to know if they're either:

Pre-determined before the game, and act as some sort of multiplier on their performance within the game engine.

Or have no impact on the game, and are just a reflection on how well the player performed across the 90mins.

There was something about this written some time back because of the keepers getting MoM so often, pretty sure it explained how the ratings are calculated, but finding it may be a problem lol.

Maybe our Charles knows something about it