You do know, that Borussia Dortmund was basically driven into ruin by Zorc´s superiors at the beginning of the millenium, right? Zorc´s work was far from perfect, especially in the beginning when he had to learn the ropes. However, since 2005 he had a very strong record in the transfer market and continued to be successful after Klopp left.
Klopp played a huge part in building the league winning team, as he is an excellent talent developer and shaper. He also had a lot of say in buying players and later became one of the main powers of attracting them. This does not mean he is an expert at discovering major talents, though. That was not even his job. Even Zorc should not get the main credit for that as while he is responsible for the scouting department he does not scout himself.
If I would had to name a single person for our success in finding talents and quality players, it would be Sven Mislintat, our head scout since 2007. He became well known mostly for finding Kagawa in the second japanese league, but there are a lot of other players, whom he discovered early. Lewandowski, Aubameyang, Dembele and Guerreiro to name a few. Mislintat is one of the best scouts in the scene, probably the only one who rivals former Leverkusen now Bayern head scout Michael Reschke as the best in Germany.
I find it amusing that so many want to pin the success of Dortmund on a single person (depending on the club they support) when most of it were team efforts and had far more people involved behind the scenen, who contributed a lot to the success. Liverpool signing Klopp got them a great coach in a lot of areas and has the potential to improve the spirit around the club. There is a lot more than signing a top coach to it to make them successful again, though, as this is just one part. In Dortmund there were a lot of people who are great at what they do together at the right time. There is no guarantie that this can be replicated by Liverpool.