Hernandez's brace helped United battle back from 2-0 down to eventually win 3-2, and Ferguson believes that his lack of participation in this summer's Olympic Games has played a part in his form.
The Mexican striker had previously played in the 2010 World Cup and the 2011 Gold Cup, and Ferguson is delighted that his side are now reaping the rewards of a rare rest for the 24-year-old.
"The thing that is making the difference is he got a proper rest in the summer," said Ferguson.
"It wasn't exhausting in the way it had been in the previous three years. He was tremendous the other night.
"He is such a dedicated footballer and professional in every training session. He's a really terrific player and the good thing is that he is still improving."
Hernandez, who was prevented from going to the Olympics by Ferguson, would have been part of the Mexico squad that went on to win the gold medal.