In my assistant manager's of end of season training report he mentioned that my captain a 26 year old midfielder has declined as a footballer over the season and he has not had any big injuries over the course of the season either. Would I be correct in saying that in FM 2012 instead of most the players peaking at 29/30 or so it depends on more the individual player and some players will peak earlier than others.
It might not be a massive decline though. Could be a few points that the assistant/coaches spotted immediately. I'd give him another year and if he's playing regularly and still shows signs of decline try and cash in.
It could just be a natural low point on a wave really.
When a player "maxes out" their potential, their stats often fluctuate up and down a little based on happiness, morale, small niggly injuries, jadedness, fitness, form and other factors. It may be that in three months he'll see improvements and be back to where he was.
kenco is probably correct with his assumption also if he is an early peaker like you said in your OP then they usually deteriorate quicker but injuries are the main factor in my game Fernando Torres injured his knee now all speed stats are down to 12 with finishing and composure down to 12 and this was at 29!!! so its not unheard of I believe you will have to make a new training schedule to the one that made him max out his potential because now he is a but older he may not take to it like he did when he was under 23 at least my players never take to the old schedule when this happens