Why has the signing of Cristiano Ronaldo not uplifted Manchester United?

Yet again Manchester United fell shamefully in the hand of newly promoted Watford. This is Manchester United's fifth loss in seven Premier League games, winning just one and drawing one. 

At the beginning of the season, one would have thought Manchester United would finally have it all figured out with the return of club legend and five times Ballon d'Or winner Cristiano Ronaldo but the reverse is the case as they are currently having the worst moment in the club's history.

The problem is hidden in plain sight but Manchester United manager Ole Gunnar Solskjaer is finding it difficult to see. His game set up can't solve the problem the club is facing right now and Cristiano Ronaldo won't make a significant difference. A team that lacks coordination from the back to the front won't be able to score goals needed to win a match. 

The backline is disconnected to the midfield and Ole Gunnar Solskjaer has been experimenting to solve it all to no avail. Cristiano Ronaldo was brought in to stay inside the box and score goals, what happens if the ball didn't get inside the box? That actually is not his fault, it's either the teammates or the manager doesn't know how to set up games to get balls in the box. At age 37, Cristiano Ronaldo cannot do all the running and shooting like before and Manchester United will be disappointed more if that's what they are expecting from the Old guy.