The France under-20 international was on the bench a few times for the Gunners, but he rarely got the chance to play in a competitive game.
"It was hard for me to stay three years there, knowing that I was almost never playing and that I only participated in training," he said to the Evening Standard.
"It was a very complicated situation. It was not easy to leave Arsenal but the loan I made here last season from February to May weighed heavily.
"It's a family club here, I needed that."