The Ivorian has failed to live up to his club record £72m price tag since joining from Lille last summer.
Campbell told Football Insider: “I do not think they made an error in his signing, not at all.
“Mikel Arteta wants to work with him. I think he has a big future at the club because he is a very talented player.
“He has done some things that were not quite right, one of them being the sending off at Leeds.
"He is suffering right now because he cannot help the team in the Premier League but he will come back better.
“With a bit of luck, everything will be fine when he does return."