In his column for the Daily Mail, Keown wrote: "Contrary to what many people think, I found Ashley very likeable and willing to learn when he came on the scene at Arsenal. He had a great deal of respect for senior players because he was an Arsenal fan living the dream just training with us.
"He was impressive in training but we only really stood up and took notice - including Arsene Wenger - when he made his first-team debut.
"There are some players who look brilliant in training and don't really perform in a game and then there are others who don't seem special in training and save their best performances for when it matters. Ashley was the latter."