Looking at hind limb structure, many field dogs are too straight behind...and many show dogs are over-angulated and sickle-hocked to the point of losing power and drive. Again, extremes....but different in their existence. It's not all that common for field trial breeders to look hard at rear structure and make breeding decisions with that in mind (it's way down the list, as a rule)...while many of the show dog folks select for the over angled extreme. One side ignores it, the other side over-does it.
Having said that, I do believe there is a correlation between too-straight hind limb structure and CCL tears. However, one also has to take into consideration the work the dog is doing. A hard running athlete is more likely to injure itself than a dog that does no strenuous work. I've seen some show dogs that are so over-angluated in the hocks that I'd expect plantar ligament issues if stressed. And if you really want to see a show dog that is ruined in the rear, take a look at the horrible hocks on the Gordon Setters...yikes! Some of them almost make the show German Shepard Dogs look normal.