In the graphic above we see two very attractive animals. The left photo shows an exceptional topline and backline. The photo to the right shows a good topline and a good backline that has been artificially created by good stacking. Note that the right photo the dog is bridged. Were the front feet under the whithers we would see a different picture of this animal. Its back would be more roached and the short loin would become very apparent. This dog is also goose rumped. Note the red lines and the gap between the backline and the tail set on both photos. This short loin is confounded in the animal on the right by the goose rump in which the pelvis is short and too angled (almost tucked under the dog and not to be confused with a good slope).
Below is a study looking at overall conformation with a focus on topline. All these dogs are wonderful animals but we must study conformation to understand how to produce better animals.