The 70-year-old manager believes the reason for the Mexican's stunning recent displays has been down to a summer break, after the striker suffered from playing 'too much football'
The 70-year-old manager suggested the Mexican suffered from playing too much football in his second year in England, losing the predatory instincts which saw him score 20 goals in his debut season.
And the Scottish boss believes the 24-year-old will make amends for last season's poor form and fight to regain his place in the starting XI at Old Trafford - but suggested he may be better as a 'super sub'.
"When we examined [Hernandez's] previous summers the answer was there," he told the club's official website.
"You can play too much football, there's no doubt about that."
Hernandez only managed to score 12 goals in the 2011-12 season, but the striker could break that number if he continues with his impressive form.
Ferguson continued to praise the striker following his hat-trick against Aston Villa to give the title contenders all three points in a hard-fought 3-2 victory at Villa Park.
He continued: "He is instinctive in terms of space and movement. That was the attraction when we first saw him. His movement, his speed off the mark, attacking the ball, and he is good at finding space.
"His goals last week [at Villa] were good examples of that. With the first one, he's scored a few like that. But his hallmark is definitely the type of goals he scored with the second and third ones."
But the 70-year-old remains unsure if Hernandez will begin to start games, hinting that some players are better at being the 'super-sub'.
"Some players are good substitutes but others are better when they start games," Ferguson added. "Ole Gunnar Solskjaer would watch a game quite closely and concentrate on what was happening on the field.
"Maybe Chicharito is the same, it's difficult to say."