First flaw I see- WHAT straight line from head to tail? True straightness refers to not being crooked, i.e. being equally supple and able to bend on both sides. Even if you're talking strictly breed show standards, nowhere is it written that there shall be a straight line from nose to tail in any context. Horses win all the time falling through their inside shoulders or driving with their heads constantly off to one side. Second flaw- I don't see how an overcheck (which controls how high the horse's head must be and how much longitudinal flexion he may have) has anything to do with forcing him to be straight from front to back. See above regarding horses in overchecks constantly going around counterbent if their drivers ask them to! Third flaw- connecting the overcheck directly to the crupper is working from a mistaken idea of how the horse works and carries himself. They aren't rocking horses; you can't tie the head to the tail and push down on the rear and expect the front to come up. You can push the back down behind the withers and get flashy front end action if the horse is built for it, but the hindquarters will trail along behind and the horse will be unable to work under himself unless he's exceptionally gifted. In order for the average mover to get his hindquarters under himself for powerful movement, he must tighten his abdomen, flex the joints of his hindquarters, round his topline and lift his withers and the root of his neck (incidentally causing him to bridle up) to free the shoulder and allow reach in the stride. The topline cannot lengthen to allow this when confined by a tight check. A finished horse learns to round himself up into the check to get the most possible length out of it, but a green horse will be brought up short and discouraged from the necessary stretching.
