Drops are smaller is probably true, but it is still early to say.
Stamina level is not going up, yet the players can play as if their stamina level was higher than it actually is. If this is what you mean by direct impact on the game engine, I am quite sure about it. I have seen a significant grow in minutes for opening players, and it seems very logical that it is the result of the new trainer.
As for the rest - it is speculative and was presented as such - preliminary thoughts