Villas-Boas, who takes his team to Goodison Park, thinks Everton would be in a much worse position had the 49-year-old not taken the helm 10 years ago.
"He has done tremendously well," the Tottenham manager said.
"He has changed the mentality of the club. They went through incredibly difficult situations financially and has always built strong teams.
"His scouting is perfect, his training is perfect, the way he motivates his players also makes a difference as you see them on the pitch and they are extremely competitive.
"His teams always seem to improve year after year and that is not always the case. Going to Goodison Park is one of the toughest games."