PROBLEMS grow for the Millers after their 12th defeat from 17 games.
They have been undermined by a defensive incapability and their goals against tally is 41 – the highest in the Football League.
That has left Kenny Jackett unable to make an impact following his appointment four weeks ago and his side are already 11 points adrift of safety.
“We are still struggling to find a defensive set-up that can keep us competitive,” said new boss Jackett.
“We started the game pretty well in the first 20 minutes, we had a lot of it, we had the ball and made inroads but then we gave two very poor goals away on the break when we were in good positions.
“The second half was similar, we were playing in and around our box and then gave away a very, very poor third goal. The key moments took the game to them. The outstanding statistic which is disappointing again is the goals against column. It’s frustrating.”
Derby chief Steve McClaren is happy with the progress his side are making.
Tom Ince and Darren Bent scored within four first-half minutes of each other to put them on track and then a second from Ince applied gloss on a win that sents Derby into the top half.
Ince had two penalties saved by Lee Camp but tucked home the rebound from the first.
McClaren said: “Five or six games a go we were wondering if we would ever score, but now we are creating chances and credit to the staff.”
Derby County: Carson, Baird, Keogh, Pearce, Lowe, Hughes, Johnson (Bryson 82), Butterfield, Ince, Bent (Vydra 69), Russell (Weimann 62). Unused substitutes: Shackell, Anya, Hanson, Mitchell.
Rotherham United: Camp, Fisher, Halford, Wood, Mattock, Adeyemi, Forster-Caskey (Vaulks 62), Taylor (Brown 62), Newell, Odemwingie, Ward. Unused substitutes: Kelly, Price, Fry, Belaid, Yates.
Referee: O Langford (W Midlands).