It is my understanding that this number reflects a players mastery of a position and affects how well the player performs relative to his ratings.

Is my understanding correct?

Also, does this number increase in value over time as a player plays in games and is developed by coaches? Or, is it a fixed number that limits a players potential relative to their ratings?

Yes, affects how well they master the position and goes up as they play that position more.

I am baffled and confused by this rating Titled "Skill" I wasn't ever seeing it go up or down for anyone on my roster...so, I decided to create a new league and sim 10 seasons while tracking a single team. The skill rating over 10 seasons did not change even 1 time for any player on the team roster over those 10 seasons. Is that a glitch or does "Skill" perhaps serve more as a hardcoded set number that indicates a player will always under-perform relative to their other ratings?

did you submit a bug report? this seems like an important thing to get fix. hopefully a quick fix as well.

i think bugs can be submitted here: https://wolverinestudios.freshdesk.com/support/home

I did not because I do not know if it is a bug or me misunderstanding the function of the "Skill" rating. Also, there is always the possibility it is just really bad luck on my end with the players being signed. I did do the my testing run at a lower prestige school so bad luck with signings is a definite possibility.

Yea, I found the issue. Currently the regular attributes will go up during the year but not skill. I updated it for a future patch.