That basically means he's almost hit the maximum level that he can be trained and receive a pop. He's a 27 year old, which means his training is gonna be REALLY slow. You'll know a player has hit their cap when it takes weeks for them to pop (this could work in conjunction with a player's age).
You would be better off getting an 18 or 19 year old for cheap. The time it would take for him to reach 100% would be better spent training a much younger player.