not saying this is what happened here. but here is my theory: Transfer managers get a part of money when a transfer takes place.sometimes directly and officially and other times unofficially. The player agents do take a cut themselves, depending on the transfer ammount. Many times in order to make that profit bigger, they give a part of their profit to the transfer managers, as they are the ones who sanction the invested sums from their clubs. Some player agents see this as an investment of making friendships and form strong ties over big club transfer managers.
When such deals happen, when a virtually unknown, unneeded and unwanted player, is given such a huge fee, from a big club to a smaller one, there usually is smth darker going on in the background, someone is making a profit from Juve's money...