The Bulgarian is due to return to Old Trafford on Saturday for the first time since moving to Fulham over the summer for significantly less than the 30 million pound fee that brought him to Manchester from Tottenham. While Ferguson concedes that Berbatov is not an industrious player, he insists that the 31-year-old's goalscoring rate was impressive during his time at United. Berbatov's reign at United included a Premier League-best 20-goal campaign in 2010-11.
"I don't think Dimitar was a failure here," Ferguson told reporters. "Some people like to see players run through brick walls all the time. Dimitar is not that type of player, but he is a very talented player and he had a decent goalscoring record here."
The Scot also expressed his belief that Berbatov, who has seven goals for Fulham this season, was unlucky to be overtaken by Chicharito in the pecking order after the Mexican's "fantastic" debut season at the club.
"That was not a problem for him," Ferguson said. "The problem for him here was the way we wanted to play and the selections I had to make. When you have choices you hope to make the right one. Chicharito had a fantastic first season with us, and as time went on he became a more regular player than Dimitar."
Ahead of the fourth-round meeting with Berbatov's new team, Ferguson also underlined his ambition to win his sixth - and Manchester United's 12th - FA Cup.
"We all know at this club that we haven't done well in this tournament for a few years now," Ferguson said. "It's a cup which has fantastic appeal, given our record in it. We have the benefit of a home draw, which I always say we would want."