Captain Tommy Rowe scored for the third time in four games to put the visitors ahead on 14 minutes before Tyrone Barnett doubled the advantage.
Tranmere then saw Andrai Jones sent off for bringing down Barnett in the box, with Grant McCann dispatching the penalty, and Britt Assombalonga and Mark Little both scored in the second half.
Rovers have now conceded 13 goals in four League One games and after taking second spot in the table Ferguson admitted his side seized their opportunity.
"Normally Tranmere is a difficult place to come to and the games are always hard here, but we were comfortable this time and it is very rare you get games like this here," he said.
"I was please about the clean sheet and we were very professional in the way we went about things.
"We got ourselves in front and scored two excellent goals before the penalty.
"When they went down to 10 men we made sure we didn't get complacent and we knew we could get more goals.
"I thought we started the second half a little flat but the fourth goal picked us up again.
"We controlled the game and of course goals do change games and we were very clinical in the first half.
"We are pleased to have won four on the bounce in the league but the start to a season is 10 or 12 games so we are not getting carried away."