The midfielder has only started two league games but played a match-winning role in Wednesday's Champions League success over Wolfsburg.
Ferguson believes Carrick, 28, often starts the season slowly and the England midfielder insists he trusts his manager's judgement.
"Just because you sit out one or two games doesn't mean he's fallen out with you," Carrick said. "It's just a case of looking at the long haul and making sure everyone is fresh throughout the season.
"You can get a little bit frustrated but you trust the manager. Of course I want to play every game but it's a long season and you have got to patient.
"Look around the squad at the quality we have and no one is going to play every week. I've been here long enough that I know how things work. I have been in and out but that's just how it is, everyone is going to be the same.
"We trust the manager and the teams he picks and it works. As long as we are successful at the end of the season, everyone's happy."