I've noticed that some big beers have different vintages and that each year, the ABV is different and the flavor changes somewhat. HOWEVER, the label doesn't specifically say that the recipe changes each year (like with some yearly releases). Some examples: Darkness, Dark Lord, Stone Old Guardian, Goose Island BCBS. BCBS has a different ABV each year, Darkness and Dark Lord taste very different year to year, and Stone Old Guardian has a separate listing on BA for each year. Whats the point of vintages for these beers? Do the recipes for these beers actually change every year, or is it just difficult to control the final ABV and flavor profile in such a big beer? Are huge beers with a large volume of malt and hops unpredictable?