Everton boss Sean Dyche was surprised Sheffield United captain Jack Robinson avoided dismissal during victory yesterday.
Robinson clashed with Everton striker Dominic Calvert-Lewin and shoved him to the ground. The defender was booked for the incident.
Dyche said: "The officials' performance was interesting today I thought.
"I don't know what the rules suggest but when the game is going on and their player does that [pushes Calvert-Lewin in the chest] I would suggest that is it unusual. They said it wasn't a push in the face so it's acceptable.
"I don't think that we would like to think that is acceptable across football at large. But anyways that's how it is in the modern game and I am learning about it and the officials every week."