The issue with koeman and sacking him is that it kinda let's the board off the hook here. We know koeman is in crisis and can't seem to get out of it, if he is sacked on the basis of that then fair enough.
But I would argue currently that it sweeps the boards failings under the carpet yet again if that were to be the case. We have had defensive issues this season with defenders form/ 3 injured and yet koeman very publically said he wanted another defender. The board didn't deliver that defender for him and the end result is poor defensive performances this season.
Similarly up front. You look at siggurdson free kick last night and then realise that striker / cf that koeman publically asked for isn't there. Siggurdson biggest strength in his game and we failed to give him it. As much as you can have opinion on any other striker at the club, they aren't a centre forward and they aren't going to have the same impact. Plus it means without a big man up front to hold play, there is nowhere for the ball to stick to when we attack.
I'm not defending koeman by any means and would still prefer him to leave if this continues but ultimately the board let koeman down in two key areas we are suffering in the most this season, but this will be forgotten about for blaming of the manager instead. It's completely poor not to deliver those players despite the public requests from the manager. This is where koeman is failing this season essentially, conceding and scoring goals, without those factors any team would struggle.
However I would still we koeman go simply because I feel he is in a rut he cannot get out into no matter how hard he tries to. But that's football, sometimes your employers are a joke and you can't make it work even when they handicap you to that extent.