Does a player's assigned position have any impact on if and/or how much they will improve/decline in a specific skill (assuming the position coaches were equal)?

EX:
Will a player's pass rush and man coverage change the same amount as it would have, regardless if that player is listed as a DE or CB?

EX:
Do WRs improve catching faster than a RB or CB, or does it all depend on that player's "hidden" ultimate rating, which doesn't change no matter what? If I move a WR to CB, will his catching improve just like it would have if he remained at WR?

If a position change is chosen the potential max will be effected depending on that specific position . The rate they gain will not change , but the max potential will drop if the changes warrants so.

I would think a wr to db would limit the players max catch rating but only to the extent of how long he played db position switch . I know a QB switched to RB will lose accuracy , and I have switched oline to dline in hopes his 99 volatility boom would have an effect on his pass rush and run defense , but that was not the case . There his pre built max ratings for an oline man were the only ratings that boomed.

The ratings that a player improves on is linked to their position, and you can identify what attributes he'll develop by looking at the position coach's attributes. Any developable attributes not in the position coach's attributes will slowly decline.

Thanks

Piggy backing off this........... Nearly every time I've drafted a TE or FB, they never seem to bust, lucky? I was wondering, if I changed all my drafted players into TEs or FBs whether its possible to 'loophole' the whole draft bust/boom conundrum?

No, the position a player is assigned to has no bearing on whether they will boom or bust.

So do some positions have more of a liability to boom than bust?

Just one more (hopefully) question.

So, does this mean that a player's run/pass blocking, ball carrying, etc. would improve/decline at the same rate regardless of whether that player is listed as RB or FB, because they have the same position coach?

That is correct.