The 27-year-old picked up the Player of the Year award at Old Trafford last season but has failed to recreate that form in the current campaign, scoring just once in the Premier League.
The Ecuador international has acknowledged his performances have taken a dip but claims injuries have not helped his cause.
"It's not been quite the season I would have hoped on a personal front," said Valencia, quoted in the Daily Mirror.
"The injuries I've had have held me back a bit. I still get the odd twinge from the last injury I had to my leg and that perhaps affected my progress slightly."
Valencia joined United from Wigan Athletic in the summer of 2009 in a deal reported to be worth in the region of £16million.
Valencia was fantastic last season. He might be somewhat limited in his repertoire of skills but what he did he did brilliantly and I don't remember much controversy about his being given the no.7 shirt. Sometimes players just have bad spells, not just a game or two but whole seasons -- if you've read Gary Neville's autobiography, you'll see that he was so concerned with his lack of form around 2000 and 2001 that he considered hanging up his boots. Hopefully Valencia is merely suffering from a similar temporary loss of form.- Griff