The 39-year-old former Wolves defender spent a year in charge of the Bucks between 2016 and 2017 before returning to Molineux as a youth coach.
He was then handed a route back into management with Forest Green Rovers - helping them to League Two promotion after just one season at the club.
On the back of that success he became the new Watford manager in the summer - but after just ten games the club, who have appointed 21 managers in just 12 years have relieved him of his duties.
And it has been confirmed he will be replaced by former West Brom boss Slaven Bilic.
Watford owner Gino Pozzo said: “As with all decisions taken by the Board, I believe this change to be in the best interests of the club,” says Hornets’ owner Gino Pozzo of the move.
“We felt Rob had enough time to show us the identity of his team, however performances haven’t reflected our hopes and ambitions.
“Now we must move forward, and, in Slaven Bilić, we have secured the services of an experienced coach who has recent experience of promotion to the Premier League.”
After taking the club Bilic now becomes the club's 21st manager in the last 12 years.