'Men against boys' ... Rival manager Lee Johnson reacts to the quality of Rotherham United after Millers' win over Sunderland
Sunderland head coach Lee Johnson said: “It's a really poor day for us. Their game-style completely nullified us.
“It was men against boys today, from start to finish, it really was. We looked leggy and we were everywhere the ball had just been.
“I am hurting badly. The fans and the players will be. Whether it's a change of personnel or tactics or additions in January that is needed, there is clearly something that we have got to snuff out to be more solid when we are under the cosh.
“If you are a good team, you are under the cosh for four or five minutes, but if you're a bad team, like we were, you are going to get runs of attacks for 70 minutes of the 90.
"A lot of the play was down our left and it's a glaring weakness in terms of if we don't have a good day it's quite easy to disrupt us on that side."
Rotherham have hit 21 goals in their last six outings and are the form team in the division.
They were were dominant for long spells of the game and made it pay with braces from centre-forwards Michael Smith and Freddie Ladapo and a header from Michael Ihiekwe.
Sunderland had Aiden McGeady sent off after the break when the winger picked up his second yellow card for a late lunge on Wes Harding.
Millers manager Paul Warne said: “It's always the strikers who get the headlines. They were two great finishes from Smithy and he could have had more.
“It was a good day at the office and obviously I am pleased. At the moment we are respectful of the opposition but not in awe of them. If we play at our best, someone has got to play really well to beat us.
“I thought we were really good but I am still disappointed with the goal we conceded.
“We are trying to win every game we play in and sometimes you don't get your just desserts but this was one of those games where we created a few opportunities and we were fortunate enough to take five chances.
“We knew it was going to be a hard game but I always think if the lads play at their very best then they are very difficult to play against.”