While this has been a very strong period for the refining sector in general, and one of the best years ever for HollyFrontier (NYSE:HFC), the company still dropped nearly 4% on its earnings release due to missing analysts' earnings per share expectations. In this video, Motley Fool energy analyst Joel South tells investors why feedstock is so cheap at the moment due to the glut in oil production, and how HollyFrontier is even more levered to this cheap feedstock than its competition. He also explains what was behind the earnings miss, why it won't affect the company again beyond this quarter, and why now might represent a great buying opportunity.