This was a big night for goalscorer Gerard Pique, as well as Danny Simpson, Jonny Evans and Chris Eagles.
"I think that they are improving. Training with the first team all the time helps them, but I don't think they've had a lot of football," Ferguson said. "But we won't be afraid to play them because they have the temperament and ability to do that.
"I think it [the defeat against Coventry] was a shock more than anything. I don't think they were ready for a game of that nature and forgot the golden rule of cup football, which is that if the opposition are up for a fight, you have to fight back. But tonight they were better prepared mentally."