Why?
Do you mean why would this formation be a disaster?
In my opinion it's an extremely outdated formation that simply would not work. How many teams in England, Spain, Germany, France etc use this formation on a regular basis? If there even are any, is it successful?
The vast majority of top level teams now use some variety of 4-5-1 / 4-3-3. To counteract this and control the midfield we would need two very good wing backs who are not only good defensively but can also support the midfield three. Would you trust Brunt / Dawson / Gamboa / Pocognoli with this role?
We also lack creativity in the middle of the park - the midfield three would end up being Fletcher, Yacob and Morrison or Gardner. I would say the strikers would get even less service than they do now.
Just my opinion, but I don't think this would work at all for us.