"Sometimes I feel being good defensively is a crime, but that is a way of getting results", he said.
"The way to do it is ignore the players who are injured, give confidence to the players who are available".
Herrera was initially unable to break into the United team this season but after injuries to Marouane Fellaini, Michael Carrick and Paul Pogba, he's finally found some game time for himself. We brought a kid, like Benfica does, because I don't have another solution.
They'll be looking to get back to winning ways in the Premier League when they visit Huddersfield on Saturday.
"I think when he signed for Manchester United, I don't think anyone thought was going to be at United for 10, 15 years like Sir Alex Ferguson".
A three-year spell at Portuguese giants Benfica helped Nemanja Matic develop into the player that he is today, the Manchester United midfielder said ahead of Wednesday's Champions League clash with his former club.
He was substituted soon after and Mourinho added: 'I thought it was cramps, I thought it was a bit of fatigue, but no it was something he felt in his knee. They went from top to bottom - we went the opposite way during the match.
"We are happy, we have nine points, won the match, didn't concede goals, the game was calm, team was compact, control and nearly there, I think one more point to qualify maybe a victory to finish first, so all good".
"We had control, some difficulties in the first 30 minutes but then we controlled the pitch".