However, Bould believes that the 22-year-old has proven what an important player he is for the club by showing his versatility.
"Aaron has been fantastic, seeing him in day-to-day training, he works extremely hard," Bould told Arsenal Player. "He never moans, gets on with his game and has done everything he's been asked to do. He's physically fantastic and he gives something to the team. I think he's improving all the time.
"The great thing about Aaron is he never looks tired. He's never weary. He adds something to the team, he gives that physicality and on the ball he's improving all the time.
"He was getting a bit of stick [from some supporters] to begin with and I think he felt that a bit. It takes a big character to come back and he's come back massively."
Arsenal travel to West Bromwich Albion on Saturday.