Earlier in the week, Mulligan claimed that he could not be expected to be as good as Gronkowski, but Brady has said that the duo can both help the team as they look towards the playoffs.
Brady told reporters: "Yeah, they can both definitely help out, no question. They've been able to contribute in the role that they've been in, that we've asked them to do, so I think now the role's going to be more.
"They're going to play more, because Gronk's not in there, so someone's got to be in there. That will fall on the backs, that will fall on the tight ends, that will fall on the receivers, anyone who's got an opportunity to produce while they're out on the field.
"If you're an eligible receiver, then you've got to do something with it, so we either run it better or throw it better or catch it better or run with it after the catch. Rob not being out there is not going to be an excuse for us."
The Patriots are on the verge of winning the AFC East for the fifth successive season.