This is a common challenge in all food production. With numerous factors like variations in malt and hops, dealing with billions of yeast cells, seasonal water chemistry changes just to mention a few of the 1000s of potential pitfalls, sometimes things may not go as planned. While there are minor adjustments we can make such as tweaking pH levels or adding unfermentable sweetness, if these solutions don't resolve the flavor issues and you value your brand, a drain pour is necessary.