Bartley left the Gunners in the summer.
Wenger told arsenal.com: "He had a good game. He had a little bit a lack of experience. He was especially impatient and I couldn't promise him to play with the number of centre backs we had. He came here [to Swansea], he has not played a lot, because he has been injured.
"We bought him when he was at Bolton, when he was a young boy of 16 years of age. We know he has the quality. He played at Rangers. Sometimes when the players have been out on loan and have played a lot, they do not want to wait anymore when they come back."