Nuhiu has faced the brunt of some Wednesday supporters' criticisms, with his languid style coming into focus.
However, Carvalhal insists that the target-man is working hard and he says that he was pleased with the way that he linked up with new strike partner Fernando Forestieri in the side's 3-1 defeat to Burnley at the weekend.
"It's [the criticism is] normal in football," he said to the BBC. "When the players come to a club they start improving, with a new coach and a different dynamic. Some players play better in this new dynamic, some players don't play so good. It is normal. These kind of things can happen with the players.
"Nuhiu is working hard and trying to do his best, this is the most important thing. He had a good connection with [Fernando] Forestieri against Burnley. I was very pleased with them."
The partnership between Forestieri and Nuhiu has the potential to be a very productive one for Wednesday, with the pair offering differing qualities.
Nuhiu is aerially dominant, whereas Forestieri is evasive and creative and he should provide the 6ft 6inch striker with a constant supply line.
When given quality service, it will be up to Nuhiu to prove his doubters wrong - as his current boss is clearly a fan of his talent.
Nuhiu finished last season as the Owls top scorer, with 11 goals in 47 appearances and his task will be to increase that total this time around.