I perfectly agree with what you said in regards to player regressing athletically. I used Barnsey's sliders from 2K19 for a good chunk of the year which has the same philosophy to what you're doing here so I understand. I have no issues your sliders at all don't get me wrong, I didn't even say anything about physical attributes.
I will say though, in my opinion at least, the consistency ratings don't get better or remain the same at the twilight of an aging player's career. For Shot IQ though, I agree that players get better with age in identifying which shots are good and which ones are not. But what about on how they can consistently contribute offensively or defensively? For instance, Nowitzki was wildly inconsistent (in terms of offensive production) in his final year.
I will adjust though, your sliders are still excellent.