Wimbledon boss Stuart Murdoch believes his side must be more like Rotherham if they want to haul themselves out of the relegation zone.
The Dons were well beaten for the second time in just four weeks against the Millers and are still firmly rooted to the bottom of the table.
Dean Holdsworth did fire in from the penalty spot, but it was too little, too late after headed goals from Shaun Barker and Martin McIntosh had put the visitors firmly in command.
And Murdoch said: "It is hard work being a Wimbledon supporter. It's hard work being a Wimbledon player and it is especially hard work to be a Wimbledon manager.
"The problem is that we are not functioning as a team right now. We have individual talent with reasonable amount of ability, but we have to realise it is a team game.
"The team ethic is not very good at the moment, whereas that is what Rotherham are excellent at. They all work hard for each other, they know their jobs and they get on and do them.
"I'm not sure our players know how to work for each other and pull together out on the pitch and we also don't seem to be learning our lessons." Barker made the important breakthrough just before the half-time whistle, beating two defenders in the air with a stunning leap and powering his header back across goal and beyond the reach of keeper Banks into the far corner of the net.
It was the least they deserved as Chris Swailes had earlier seen a header crash against the post, while Martin Butler had miscued from just eight yards with the goal gaping.
Rock bottom, Wimbledon looked short of ideas going forward with Wayne Gray's two weak headers their only efforts of any note before the break.
Murdoch's side did liven up slightly at the start of the second-half and Adam Nowland was unfortunate to see his 25-yard drive smack against the post after beating Rotherham keeper Michael Pollitt.
But the Millers struck a killer blow on 67 minutes as captain McIntosh was left unmarked and unchallenged to power in a six yard header from Carl Robinson's corner to make it 2-0.
Holdsworth did pull one back with 14 minutes to go as he converted from the spot after Paul Warne was adjudged to have fouled Patrick Agyemang, but Rotherham held on fairly easily for all three points.
And Millers boss Ronnie Moore said: "I thought we deserved the win and could have got a few more goals.
"I don't think it was a penalty and that made us nervous towards the end, but if we had taken a few more chances before then we would have gone on to win by two or three.
"So although we are delighted we know there is still work to do because we need to be more ruthless and score more goals when we get the chances."