Michael Beale has explained what his biggest ‘concern’ is after Sunderland lost to Birmingham City. Sunderland massively overachieved in their first season in the Championship, narrowly missing out on the play-off final to Luton Town. However, it now appears that they have only gone backwards. Since bringing Michael Beale in to replace Tony Mowbray in December, the Black Cats have won four out of their 12 matches and now sit tenth in the league table. The defeat to Birmingham was their second in a row and now leaves them four points from sixth place. It comes as no surprise that many supporter…