Technical director, DoF... shares similar situation just like manager and head coach thing. SAF as manager can take a lot more responsibility at the club. He can have his assistant manager doing a pseudo manager job for the team in his place, while he's spending time doing technical director/ DoF such as selling the club to prospective recruits to the first team, even the academy.
So all these technical director, DoF titles from different clubs don't necessarily mean the same role. If Kehl is in succession plan to replace Zorc, then he's not only doing the easy job, but also involved in every aspect of his supposed next job.
Supporting from below is not the same as mentoring with authority from above. You learn to cook from your chief chef not from ingredient suppliers, ingredient preppers, janitor... because once you become the chief chef you're tasked with authority to make change. Your underlings would always try to make themselves positive in your eyes. If you don't advent yourself, you better have a mentor (higher in authority) to burst that bubble in order to show you all the in and out.
As for our structure, even our DoF doesn't have authority to act on behalf of the club to sack the manager. Already very different to Dortmund set up, so it's not a straight forward comparison.
There is no evidence of Fletcher doing a good job. There is no lacking of talent in our youth set up, before his time. For the first team, there are no players we sign that's solely evident based on whatever vision we supposed to sell to them; because we lack an identity to begin with.