The Hornets on Sunday appointed their fifth manager in the last 18 months with Xisco Munoz arriving to replace the sacked Vladimir Ivic.
Ivic only spent four months in charge of Watford and even won the Championship manager of the month award for November - two weeks before being dismissed.
Deeney has been through thick and thin at the club over the last decade and discussed the latest Vicarage Road managerial change on talkSPORT.
He said: "I think if you look at the ownership and what they do, they don't wait around.
"I think within the hour of [Javi] Gracia being sacked they announced [Quique Sanchez] Flores had come back… within the hour.
"So you put two and two together and think it is one of those things where they must have a back-up plan ready to go."
Deeney also insisted he had nothing to do with either Ivic's sacking or Xisco's appointment - hitting back at social media claims that he runs the club.
"I am not there for those conversations," he added. "Although people think I actually run Watford and I make every decision, I am not there for any of it. I am reading it on Twitter the same as everybody else."
Asked if he would ever consider becoming Hornets player-manager, Deeney continued: "Not for me, thank you.
"I'm 32… I still want to play and I'm still active.
"When you go over 30 people think you are 39 - that's it. You're 31 but in people's heads you are 39 because you must be coming to the end of your career.
"If I wanted to be the manager I wouldn't be here, talking the way I do. You have to change your tone and talk a certain way, and do your badges.
"I want to play football.
"If I wanted to be Watford manager, I certainly don't have any credentials to do that.
"And, to be totally honest, why would I go into a job where you are probably going to be sacked in five months?"
While co-hosting Monday's talkSPORT Breakfast, Troy Deeney responded to frequent claims on social media that he 'runs Watford' and dismissed any suggestion of becoming player-manager.