Over the past 20 years, Spain has experienced a dramatic upheaval in its deeply rooted wine industry. New regions have gone from obscurity to success; old grapes have been recovered in brilliant new wines. The epicenter of this revolution in style and character has been the country's most prestigious wine region, Rioja. Beginning in the 1990s, a vigorous debate pitted tradionalist bodegas against a new wave of vintners. Though the polemics have been fierce, overall quality has improved in Rioja, and great wines have been made in both styles. A few producers, however, have found a middle ground that is rooted in history yet open to innovation. Among them, the benchmark bottling, for its pedigree and consistency, may be the Cune Imperial. Wine Spectator's Thomas Matthews explains.