well... i don't think in age 24,25 you still can train them very fast...even they are the fast trainer....
i always get my fast trainer in age of 18-19...20 maybe....but seem in 21 -22... they slow down~
in age 23...they already slow ...and i won't waste green pack on them...(they become my branch or even I sell them~

and i think you can see how many match they played so that you can have a idea how long they stay with the team... i don't really focus only state...because they may not play well in one team, doesn't mean they won't play well in your team. it depends~