Rooney was suspended for the first two games during the Group stage against France which ended in 1-1 draw and the 3-2 win against Sweden. But the 26-year-old, who returned for the final Group match with hosts Ukraine, scored the only goal to push his side to the quarter-finals to face Italy.
Ferguson blamed lack of competitive football for over a month for the failure of his star striker in the Three Lions outfit. However, Wayne Rooney was heavily criticised for his below-par performance.
The striker failed to live up to the high expectations as England lost to Italy on penalties.
"He didn't play until the third group game. I don't know what his stats were, but he certainly didn't look as sharp against Italy as he did against Ukraine," Ferguson was quoted as saying by Mirror.
"If Wayne misses a couple of games, it takes three or four for him to get back," he added. Ferguson knew Rooney would struggle at Euro 2012, "He needs a lot of games and I always thought it would be difficult for him at the Euros because his last game was May 13".
With so much expectations on his shoulders, Ferguson said Rooney must get used to the tag 'England's star player'.
"That's something great players have to live with. It's a fact of life," Ferguson said.
Ferguson was impressed by the performance of Lionel Messi against Brazil and Spain's pass maestro Xavi Hernandez brilliant display against Italy at the Finals of Euro 2012.
"Apparently, in Argentina, they've never taken to Lionel Messi. Don't ask me why, but that quite amazes you.
"Then, against Brazil, he scores an unbelievable third goal in a hat-trick and that's a way of putting people in their place," Ferguson said.
"People say Spain weren't the force they were but then Xavi produced that performance against Italy [Euro 2012 Finals], man-marking Andrea Pirlo and playing off him. He was brilliant."
"Great players have to deal with these things no matter who they are," he said.
However, despite all the criticisms thrown at Rooney, Ferguson feels Rooney is reaching his peak and is consistently scoring goals.
"Where he has improved is his consistency in scoring goals. He got 32 goals last season and that's made difference to his game."
His goal-scoring has certainly given us more of a reward," Ferguson said.