Why do players attributes drop for no reason?

[Gunblade]

Asked this in the official forum but the the usual answers given were not the correct answers and topic has stalled.
There are times when a players attributes drop almost all drop across the board, around 80% to 90% of their attributes orange arrows. Occasionally one or two light green arrows if I'm lucky but usually a substantial all round drop wiping out a year, or even more than two years, of progress with no reason why and it's infuriating.
Now there will be some of the usual answers and I will pre-emptively say why they're not the answer.

Stat rebalancing: Not this, For some youth players who've had a large improvement over a short period of time yes but this topic is not about them, it's talking about any other player from young players improving at a steady rate to players in their prime improving at a slow but steady rate. Hence when the orange arrows of doom appear and you check training progress over the year it is an overall decline over the year or more.

Capped ability: Not this, as again it happens to young players with uncapped ability. Also when rebalancing it shouldn't drop 80% of attributes just to increase one. And again if it's an overall decline over a two year period then it's not technically a "rebalance."

Poor Training: Nope, Each player has done well for training always average above 7 and usually hitting 8's for some quality players.

Game time: Nope, again happens to players in their prime who are regular starters along with youth players who have played up to half a season. Perhaps some youth players could have started more but I'd find it ridiculous that they should see an overall decline because they "only" got 50% of a season which should be more than enough surely?

League level: Nope not this either. If this was the case then how did the players improve to the level that I got them to in the first place?

Form: This one not too sure but the majority (though not all) of my players have been performing well in the league so that shouldn't be an issue.

So what does this leave me with?
Any ideas?
The only thing I can think of is some kind of hidden mechanic that just randomly drops a players ability by a substantial amount for no reason what so ever, anyone know of what it is or should I just go a get the editor to put these attributes back to what they were.
I have no problem with declining players but when I'm given absolutely no reason for their supposed SUBSTANTIAL decline over a single month period then I call BS.

[Scruxx]

Are the stats really going down? Of course i saw this orange arrows in my game too, but i never realized that the stats really drop.

[Gunblade]

Oh they drop, my player really does decline even if it's 0.1 (though more often that not it's a greater value). It's never something like a whole value of 1 but a 0.2 there and a 0.3 spread over 80% of your attributes or more and boom your player can see a real overall decline in his ability and wiping out months and years of progress.

[Scruxx]

I never managed to find out where it comes from, im with you. Saw it for players who had a great form and perfect training ratings and also for players with low form with bad training rate. Its like "someone" says: Oh, he didnt is as good as i thought, Downrate! But i dont know if this has something to do with the training staff.
I didnt saw it too often in my last 3 seasons. Maybe it has something to do with the stats player skill and potential player skill, because in my new game i only buyed assistant coaches who have minimum a 14 in these traits. Even if they dont need it for an assistant coach. And the training reports always come from my assistant coaches.

Also i had an eye on the data presentation or player data, most of my traning staff has now min. 4 in these stats. But seriously no idea if this has any impact.