The Dutchman, who scored his ninth league goal of the season, in between Carroll's first two goals for the club, said that the inclusion of the striker pairing was well-received by the playing group.
He also praised £35milliom signing Carroll for his brilliant performance against City.
"The players have been very happy with signings of Andy and Luis," he told Sky Sports 1.
"Andy's scored his first goals today - it has been tough for him after injury, but he's played very well.
"No-one is more happy than Andy, but his team-mates are happy for him too.
"He's very good in air and can score with feet - he's a big threat."