Over the past five months he has gradually won his new manager over with his commitment, attitude and dedication to the cause.
Arteta is convinced the much-maligned 28-year-old has finally turned the corner.
He said: “We try to help every player to improve, first of all by making them feel that we trust them.
“Everyone can make mistakes, of course, but if they are willing to keep trying then they will get rewarded.
“Musti's attitude, the way he is training, attention levels, the questions he is asking and how much he wants to help everybody has been really good since I joined."