I'm no expert but I'll share my thoughts: It is a literal "hitting machine" that allows Bonds to release his front arm on the same plane during every swing. It largely accounts for the seemingly magical consistency of every Bonds stroke. Reasonable theory but to matter-of-factly conclude that it "largely accounts" for anything without offering any actual evidence makes me question the author right off the bat. The locked arm forms a rigid front arm fulcrum that allows extraordinary, maximally efficient explosion of the levers of Bonds' wrists. The elbow itself does basically the same thing and I really picture how that produces a mechanical advantage anyway. Just like how a pitcher's throwing motion is a long kinematic chain, I would think you maximize bat velocity by maximizing the angular acceleration of each joint. Heck, wouldn't it better if a bater's elbow was double jointed, so he would use his triceps to add energy over a greater angle? When Bonds swings, the weight of the apparatus helps to seal his inner upper arm to his torso at impact. Thus "connected," he automatically hits the ball with the weight of his entire body - not just his arms - as average hitters ("extending") tend to do. I just can't see it working like that. Bonds has performed less well in Home Run Derbies than one might expect because he has no excuse to wear a "protector" facing a batting practice pitcher. As he tires, his front arm elbow tends to lift and he swings under the ball, producing towering pop flies or topspin liners that stay in the park. When the apparatus is worn, its weight keeps his elbow down and he drives the ball with backspin. That, or swinging 30 times in a row is different than swinging 4 times in an AB? Maybe he's right but it's nothing more than speculation. Bonds enjoys quicker access to the inside pitch than average hitters because his "assistant" - counter-intuitively - allows him to turn more rapidly. Everyone understands that skaters accelerate their spins by pulling their arms into their torsos, closer to their axes of rotation. When Bonds is confronted with an inside pitch, he spins like a skater because his upper front arm is "assistant"-sealed tightly against the side of his chest. Ignoring whether that's even analogous, isn't the goal to generate bat speed, not angular velocity? At impact, Bonds has additional mass (the weight of his "assistant") not available to the average hitter. The combined weight of "assistant" and bat is probably equal to the weight of the lumber wielded by Babe Ruth but with more manageable weight distribution. Reasonable theory, although adding weight at the elbow wouldn't help nearly as much as at the end of the bat, would it? I never played past little league and have never given much thought about the actual mechanics of a bat swing, so I could be way off on one or many of these comments. I don't completely understand the physics behind a batted ball. Does the bat spend a relatively short time in contact with the ball or does a batter add significant energy by driving through the ball? I guess I could at least try googling a popular mechanics article before spouting off. http://forum.brewerfan.net/images/smilies/smile.gif Overall, it just sounds like the author is trying awfully hard to overstate the advantage that the guard gives Bonds, however.