On the way to Mainz— Joe Gyau (@JoeGyau36) September 19, 2014
It's important to note that Dortmund are suffering through a rash of injuries right now. They have a lot of missing players, which is what has opened up a place in the team for Gyau, even if only on the bench. It's not as if Gyau is one of Jurgen Klopp's 18 top players, but he still has to be playing well to make the team. He wouldn't be put on the bench if he was training terribly, no matter how many injuries BVB have suffered.
There was some skepticism when Gyau joined Dortmund this summer. He signed for their reserve team, but it was clearly with an eye of one day making the senior team and with BVB being one of Europe's better clubs, that was a big ask. Now, he's playing well, though, or at least well enough to take advantage of the opportunities injuries have afforded to him.
Jurgen Klinsmann clearly likes Gyau, starting him when the United States played the Czech Republic earlier this month. Klopp also appears to like him, giving him some chances. With both Jurgen's in Gyau's camp, things are looking up for the American.