Alright then.
Well, since the AoA change corresponds to what the real flight manual says: "with the BLC system operating normally, the angle of attack by the YYA-1 indicator diminishes by 2 to 2.5 degrees as compared to the angle of attack at the same speed with the BLC system not used."
, I wouldn't say the BLC is under-performing, unless there is something else wrong with the relation between AoA and lift in the flight model.
EDIT: Of course that's just the relative change, it might be worse with BLC than it should be and so on...