Flick has been trying all year to find a suitable replacement for Inigo and it hasn't worked out.
Eric at CB, at least IMO is not bad, but he's clearly much better as an RB/DM and with how Kounde's form has been all season we are better off having Eric over there on the right and also filling in the Midfield when needed as well.
Araujo just doesn't have the skill set to be a full-time starter in this team. Not good enough on the ball and has way too many bozo moments at the back in regards to defending at times as well.
Christensen is a fine defender, but not reliable due to fitness/injury issues, which leaves us with Cubarsi, who himself has been underfire and underperforming at times this season, but to be fair, he's still very young.
Doesn't hurt to give Martin a run of games at LCB to see if he can be reliable in that aspect.