It happens a lot, mostly with players created in new teams, it's not a bug, its's simply a player that has reached his limit and is better due experience.
A player can get more ability playing matches, that makes his rating increase, however, once a player reaches his potential his atributes won't increase from training. Potential ability is not necessarily related with player attributes.
Your scout will be more accurate and less expensive scouting an opponet's player when his level is increased, his skills has nothing to do with your players's stats.
