Roger. I’m going to assume that you really mean that the UPPER arms should be positioned equal and opposite at footstrike. If I recall correctly, you and I spoke of this before, and you clarified this at that time. My point being that, at footstrike, if the ARMS are truly equal and opposite, the glove and lower arm would be pointing upward, in somewhat of a “goalpost” position which is not the appropriate position at footstrike.[/quote]
DM, you are correct. The upper arms need to be aligned and mirror each other. The forearms can both be up, both be straight, both be down, one be up and the other down, etc. From a balance perspective, you want the forearms and hands and ball/glove equi-distant from the body. Imagine walking a tightrope - you need to keep the weight evenly spread out. (The glitch here is that the average glove weighs 2-3 times what the ball weighs. This is why so many young kids develop the habit of dropping the glove.)
Remember that this opposite and equal thing only happens for a short moment at foot strike. To hold that position for an artifically long period of time would be awkward and would mess up timing.
But, speaking of timing, that is the other reason for opposite and equal. When pitchers do otherwise, they mess up their timing. In the video posted above, it looked to me like the pitcher pulled his glove to his side and that caused him to prematurely spin out of his shoulder delay. So, in order to delay shoulder rotation, he’s got to give himself the timing to do so. I feel the fix is in his glove arm.
Tom House teaches leaving the glove out over the front foot and bringing the torso to it. As part of this, the glove it flipped over so the palm faces the pitcher and the glove arm firms up to create a stable base to throw against. So far, I’ve not discrovered any reason to refute this. A stable front side does seem to help with consistency.