If you scouted and removed him because he is a bust, you can see a faint bust icon in the lower left area of the player window.
The first week you are recruiting (offseason, first week of Transfer Portal), the menu item is checked before you go begin to load players on your board. Add a player to your board and it will be unchecked until you assign all you your hours. This got me yesterday because I had to leave and thought I had already recruited when I got back.
Coaches are not associated with a specific playbook. Dynasty year 2 and my OC left for HC of App State and I hired an OC who runs the Spread. I only knew to use the Tulsa playbook because he was OC at Tulsa. This would be less important if we have the coach's real name.
Depth Chart resets also happen when editing a player. I renamed Isaac Tull to Jethro Tull and that change removed him as my starting 3rd Down Back.