The Northern Irishman took the Anfield reins from Kenny Dalglish earlier in the summer but has not had the greatest start to life on Merseyside.
"Any young manager needs time but in the modern world you don't get a lot of that," said Fergie.
"Look at (Andre) Villas-Boas at Chelsea last season. He was a young man who lasted about seven months.
"We're in an age where patience is not a realistic thing. It's just not there."
But Ferguson did admit that Rodgers would need to provide positive results if he wants the backing of the entire Liverpool community.
"The only route for any manager is success. It's a results industry so winning matches is important,” he added.
"It's a different game from when I started. There was less pressure.
"The world has changed. The press has changed. But I always felt I needed to win games.