Pioli’s side were hammered by the capital club, who move up to third spot, one point behind the reigning Italian champions.
The defeat was also Milan’s fifth game in all competitions without a win, conceding nine goals in their past three.
“This is a delicate moment, certainly, as in the last two weeks or so we have not provided good performances or results, so we all need to do better,” Pioli told DAZN.
“We must quickly get back to Milanello and work better, because clearly we are not putting in the performances up to our capabilities.
“There are many things not working at the moment, theres mentality, tactical issues because we conceded on some situations that we certainly should’ve read differently.“I am here talking to you because I have to, because otherwise we should just stay quiet and work hard.”
Milan’s slide is cause for concern, not only with the title slipping away, but also their top four hopes, even with Juventus seemingly out of the equation after their 15-point deduction.
“Things are not working for us at the moment,” Pioli said. “Despite not creating great scoring opportunities, we did create some situations where we could’ve been dangerous.
“I think the main problem is when we dont have the ball, as there isnt coverage, we arent sharp and certainly need to communicate better on the pitch.
“We need to get back to playing the way we know how, that has to be the objective and we must do it as soon as possible.
“Our performances over the past two weeks have not been what we expected or what we are capable of. I will try to talk less and work harder.
“We do not want alibis or justification. I realise its a delicate moment, the lads will have my support and the desire to get back to being competitive.”