Gray, a free transfer signing from Crystal Palace in August 2004, failed to command a regular place in the Blues starting line-up last season through either injury or loss of form.
The 26-year-old winger also came in for a lot of abuse from home fans for some indifferent performances, most notably in the 2-1 defeat to West Ham United at St Andrew's last December.
For me Gray has everything required to be a very good player, but he has only played about two good games for Blues - the home game against Blackburn last season and the home game against Manchester United the season before last.