The backline has no speed or size, nor do they play with desire. Doesn't matter the system, they are incompetent. My guess is BVB wanted total football type players, because the one thing the back line can do is pass and shoot. Too bad they can't get their head to crosses or keep pace with the guys they are marking.
Gotze cannot stay healthy. Schurrle is old, small, and slow.
The only guys I like are Sokratis, Pulisic, Zagadou, Isak, and Sahin