Why do my players going down from 53 average quality to 50 ? 

• Tackling was added to midfielders average quality calculations by reducing the impact natural fitness had, this will most likely result in a drop in AVQ since most midfielders currently have more natural fitness than tackling skill.

Nicmo's modification that affected the midfielders of all teams. It was the same for everyone, not only yours. It was in the August 23 update on the announcement forum

Thanks 😊 

So what will happen if I increase the tackling?

Increase the Skill that been underline will increase the Average Quality of the player