Martinez accepts there's still great inconsistency in their play.
But asked if he was confident of progress, Martinez said: "Massively, but I don't think we are ready to go in two competitions and try to be successful in both. I think our priority is the Premier League.
"There have been many changes this season and situations where we need to focus on the Premier League.
"That doesn't mean it is an excuse to explain the defeat, but the FA Cup is a competition that for us is not really where we are going to be judged overall for the season.
"I understand the disappointment for the fans but I know they are going to show that togetherness as a football club and help us to turn the situation around.
"We have got 16 games in the league and our aim is to stay in the Premier League."