Ok this may sound convoluded but hopefully it'll be understandable: with a normal racquet, when the bird hits the string bed, it pushes into the string bed. You are exerting a force in the opposite direction through the shaft. Thus, everything below the point of impact wants to push forward, while there is a tendency to push away above that point. In essence, the head is bent a little. With armortec, there is a concentrated section of weight at the very tip, which also pushes forward due to momentum. (much more so than a regular racquet.) Thus, there is less head-bending, and thus the racquet head "acts" stiffer. Further, the boxy frame maxes the head "less-bendy" as well. with another racquet of the same head-heaviness and weight, more of the head weight is all around the racquet rather than just at the tip, so the effect is much smaller, because much of the weight is not above the poinit of impact. makes sense?