Borussia Dortmund have been below par on numerous occasions this season. The main problem with the team is the defense. Niklas Sule has already been a confirmed by the club has there first summer signing. Nico Schlotterbeck , valued at 30m would be a great addition to this defensive unit, offering resting time for the aging Mats Hummels. Özcan is being with a move to the team, with only a 5.5m release clause he could be brought in to replace Axel Witsel. David Raum is also being linked to help the defense. When Haaland leaves in the summer the team will be short for goals. Karim Adeyemi will be a great addition but he will not be able to fill the void Haaland leaves, Sebastian Haller would help with that. The team has struggled since Hakimi left the club, Thomas Meunier hasn't been up to par though he has improved recently. Ansgar Knauff has proved himself more than capable this season on loan at Frankfurt and with Edin Terzic probably replacing Marco Rose he would suit the system well