It's a new feature this year. Like other game elements we don't know their implications and are just guessing on what effects they have on the gameplay. Well we know for sure that you can use your coaching attributes in the training section of the team.
The amount of goals I concede from rebounds (keeper saves a shot from outside the area and an opposition player beats my defense to the rebound and has an open goal) is insane. I hope it's a reflection of my shitty, semi-professional defenders rather than a match engine problem.