Although the Mexican has shown flashes of the form that saw him make a devastating impact during last season's debut campaign, he has struggled to offer a consistent threat.
Hernandez has not scored in five games since his effort against Newcastle at Old Trafford in November, his longest run without finding the net in his entire 18 months with the Red Devils.
The 23-year-old was an unused substitute in Sunday's win at Manchester City and now appears to have fallen behind Danny Welbeck in Sir Alex Ferguson's list of strikers.
Not that Hernandez is too dismayed at the downturn in fortunes.
"There are different circumstances because I have had more injuries this season than last year, but I am still enjoying it," Hernandez told MUTV.
"I am still learning and working hard, trying to improve day by day.
"Each year it is going to be more difficult.
"In the first season, not only the defenders but also the coaches didn't know me.
"Now, and in the third and fourth seasons, they are going to know me even more.
"But good players like Wayne (Rooney), (Robin) Van Persie and (Didier) Drogba have been here five, six years or more and still play at the same high level.
"I need to keep working to do the same."