Fergie said: "There's a root to criticism quickly in football today. You go into some boardrooms and there's only about four directors but 30 or 40 hangers-on.
"They are the ones who think they know everything and are the ones who are probably laying the seeds of doubt."
Ferguson rates Jol so highly he tried to make him his assistant manager in 2003 when Carlos Queiroz went to Real Madrid.
The United boss added: "The work Martin has done in Holland and at Spurs is outstanding.
"It's just sad that there's such a knee-jerk reaction in football today."