Blackwell told the Yorkshire Evening Post: "Jamma failed to settle in at the club and that affected his performances. It's always disappointing when things don't work out and he didn't produce the kind of form we hoped.
"It was quite a coup when Jamma came here - it's no secret that Everton were interested - but sometimes things don't go as you'd like and it's been a difficult couple of years for him.
"He did play a part at an important time though and we all wish him all the best for the future."
Wright is now expected to join his former boss at Ipswich, George Burley, at Southampton.