I know that this can happen. I believe it has very little to do with the head and much more likely that the shafts in your new blades are a better fit for your swing. I have two set of irons, one set of blades and a set of forged cavity backs. I put a high launch shaft in my blades and have normal stock true temper shafts in the cavity backs. I hit the blades much higher and more consistent than the cavity backs. Because of that I tend to play the blades more than the cavity backs even though I know I should play the irons with more forgiveness.