There was nothing condescending in my post, which is unfortunately more than can be said for yours.
Among those who do test and work on the game, we haven't yet seen this ourselves.
We're not perfect in the least. Maybe we missed it, that's absolutely, 100% possible. If so, we'd really like to know about it.
If that's the case, you need to find a way to help us see what we're missing. Maybe we're wrong, but if so you need to prove it, not simply be more aggressive about it.
You've been asked to provide data and proof, yet you provided only a few isolated cases, and to keep telling others to look for themselves. Well, we have looked, and we don't see what you're seeing. You've mentioned a few cases, but not more than real life provides.
So what does real life provide? Let's look at that, to set a needed baseline to examine your claim.
Of the 100 best rookie seasons by hitters from 1970 through 2010 (so we have enough data to see if guys actually fell off of not, which we don't have with more recent debuts) between 18-23 (23 being the oldest age you mentioned) according to fangraphs, by my count 25 were by guys who did fall off significantly, within a few years of their rookie seasons. Also 4 of the top 10 did. That's not counting Fred Lynn, since though he fell off, he was still incredibly good.
Your count may be slightly different, but we can probably conservatively put the number around 25%. For example you mention Bob Horner as a guy who fell off early, but I actually counted him as one who didn't, thus one of the 75% "good guys". My count was fairly quick though, so it may be a bit off.
So these guys do exist in real life, as you've admitted. Thus, the question is not whether they also exist in OOTP, but whether there are significantly greater percentages of these guys in OOTP than in real life?
So with the default aging settings in a modern MLB environment, is the percentage of batters in OOTP that first make MLB between 18-23 and put up rookie seasons above 2.2 WAR, or so, and them fall off very badly within a few years significantly greater than 25%? If so, how much greater? Those are the questions you have to answer in order to get further with this discussion. There are other questions beyond that which would need to be analysed, but that's pretty much the minimum bar for proving there's a potential issue here. Answer those and some other folks will likely pick up the ball on further analysis.
Now, the ball's in your court if you want to claim there's an issue here. Saying there's a problem 'because I say there is and here're four random examples' is not providing proof, or even enough persuasion to move the needle.
Markus is always open to changing and fixing the game, but he won't do it based on someone's whim. He requires a great deal of data and a persuasive argument before he makes big changes.
If you want something done about this, you need to find a way to actually document your claims or to at least to give the folks in a position to make changes happen a reason to credit what you're saying enough that we'll want to analyse this ourselves.
That can easily be done, we're always looking at issues with the game and areas it needs improvement, of which there are many, but you haven't done it here so far.
Convince me, or any other OOTP employee or senior beta tester, there's an issue here and this will absolutely get looked at during the development of 17. Keep not doing so and being fairly aggressive toward those who discuss this with you on top of that, and it absolutely won't get looked at.
That's not condescending, that's just the reality of how this works.