Reyna, once touted to be the next big thing in European football, has struggled for form and fitness, experiencing a drastic decline in performances. His future at the club remains as uncertain as ever.
Julian Brandt has become the team's chief playmaker in the No. 10 role, however, the departure of Marco Reus has deprived Dortmund of depth, with Brandt accumulating far too many minutes without much rest.
Signing Idumdo from Sevilla, then, could turn out to be a great opportunity for BVB to reinforce their midfield in January. The youngster only recently left Ajax for an adventure in LaLiga and has rapidly taken the next step in his career.