I seem to recall a great deal of Star Wars lore indicating that the dark side is the quick and easy path, wherein its weilders often learn powerful tricks swiftly, but at the cost of other skills, particularly with self mastery. I could easily see a Dark user like Kylo Ren, who is clearly powerful and talented, but also immature and lacking in self control, performing such a potent move, but in a rage motivated battle losing to someone inherently stronger.
This is a GREAT observation and needs to be spread all over the Internet. Seriously!