He should be sacked.
In any job, no matter what the intention is of a long term project, there has to be a minimum measure of success. Most people have things like ROI targets to live up to in normal jobs.
Marco Silva, by any metric you care to think of, has not met the minimum measure of success. Yes, it's a transition season, but that doesn't give him carte blanche to be awful.
When his only defence is "he needs time", and then you look at his track record with absolutely nothing in it to suggest giving him time is going to make any difference, then the game is up.
Sack him. Put a caretaker in until the end of the season and go from there. I fully understand the desire to stick with a manager and get a project going, but it can't be a bad manager, because you'll just end up with a bad project.