Who else was there to replace him with? We have particularly targeted that position of the pitch for new signings. Why?
Because - as Koeman has said - we knew he wasn't signing.
I've - in fairness - slated Ross a bit for not giving a clear indication to the club. It appears, though, that he did at least let the manager know 'by the end of the season'.
So we knew he wasn't signing and thus had no choice but to target that position.