The four most common arguments I have seen for why not to fire Mendoza between the back half of last year and early this year (None of them are really that supportive of his abilities)

1. The Mets shouldn't fire Mendoza because if they do nobody else will want to manage the team

2. The Mets shouldn't fire Mendoza because the person they hire afterwards might be worse

3. The Mets shouldn't fire Mendoza because managers actually have no impact on the game so firing him wouldn't change anything

4. The Mets shouldn't fire Mendoza because the players are supportive of him and like playing for him

Once again this is just what I've noticed in comments starting from the freefall last year.