I don't think a back four is the silver bullet people seem to believe it is. Having one fewer defender isn't going to turn say, Podence into a massively effective creative/goalscoring force, look at his career record.
We went to a back four near the end yesterday, made no difference as we still didn't move the ball anything like quickly enough, still don't have people who attack deliveries from wide properly, still have too many players on the park who are seriously limited in an attacking sense.