The Millers have slipped to ninth in the table after home defeats to lowly Barnet and Bristol Rovers, but sit only a win off third placed Burton with three games in hand ahead of the visit of Northampton Town on Saturday.
After returning from loan at Oxford and taking over the armband from the departed Ian Sharps, Mulls spoke to Millersplayer and said: "We had an open air meeting and we spoke at length about what needs to be done. We have meetings all the time where people get things off their chest.
"We all want the same things and the ultimate aim is promotion. We're looking for a response on Saturday against Northampton and we want to give people a joyful weekend. We've all been miserable these last couple of weekends and I understand the fans are frustrated.
"Personally I'm pleased to be back and it's an honour to be captain of a club like this. I want to be captain of a promotion winning side."