After making only 10 appearances for the Gunners, Gnabry has gone on to become a star with Bayern.
"We tried to extend his contract for a very long time and I think that Bayern manipulated behind the scenes, that if he went to Bremen he would join Bayern after," Wenger told beIN Sports .
"He was always a very talented boy who lacked confidence in some stages, but we always thought we had a player who could achieve a lot.
"He came back from a very bad experience on loan at West Brom where his confidence was destroyed. I tried to rebuild him because I believed in him."