The Red Devils have failed to replicate the success they enjoyed under the Scotsman, having cycled through eight managers, including caretakers, since his exit in 2013.
And Chicharito, who won two Premier League titles under Ferguson, has told the club it must move on to a new era.
"United need to get over the fact that Sir Alex Ferguson has gone," Hernandez told reporters.
"Would we like to have someone similar? Yes, yes, yes - but Sir Alex has gone and it is never going to be the same.
"It doesn't surprise me what has happened at United because in life it's not easy having a manager for 26 years in the way that Sir Alex did it.
"One of his greatest aptitudes, in my humble opinion, was that probably seven out of 10 players who signed worked out.
"It is like winning the lottery. Do you think anyone you hire afterwards is going to be able to do even 80 percent of what Ferguson did?"