Players often spoke about being kept on their toes by Hayes and she would demand high standards from them daily in training and matches.
A big part of her coaching philosophy has been to create high-pressure situations so as to develop "mentality monsters" that were rife at Chelsea.
Fox said when Hayes arrived, the players wanted to "show what we could do" to return to winning ways.
"With Emma, the cohesion was perfect. She had players who were hungry and wanted to learn, with a coach who is also ambitious and wants to win," said Fox.
"It just worked and we were able to win gold. We knew it was going to be a grind. Each game mattered. We were up for it and wanted to be in the moment."
While Hayes is tactically shrewd and often reacts to situations in games, Wiegman has a clear gameplan and backs her team to see it through, no matter the opposition.
She did not change her starting XI once during England's Euro win and has not sprung many surprises in her team selections since.
"Everyone is on the same page so when things change it doesn't matter," Wiegman said after England beat Spain in the Euros quarter-finals.
On route to the 2023 Women's World Cup final, Wiegman had back-up plans for England's injuries.
Lauren Hemp and Alessia Russo formed a partnership up front and Katie Zelem filled in for midfielder Keira Walsh when she suffered a knee injury.