what are buck's retrogression and his leadership abilities

I don't think Buck ever deteriorates after defeating Spitz rather he becomes super alpha dog to the pack. Buck even knows when humans, like Hal, are being stupid. Buck exercises leadership by not travelling over thin ice. By the end of the story Buck wanders from human away from control. His pack leadership days seem to bore him and his inner-wolf is calling him. Buck joins the wild to take his rightful place as a dog of the wild wilderness.