Dave Eggers preceded his memoir “A Heartbreaking Work of Staggering Genius” with a section titled “Rules and Suggestions for Enjoyment of this Book.” It’s a brilliant attempt to disarm the reader and preempt criticism. Among its warnings, referring to chapter four: “The book thereafter is kind of uneven.” (Disclosure: Eggers edited my work at two magazines in the ‘90s.) Barack Obama shares Eggers’ talent for managing expectations. “There will be false starts, there will be setbacks, there will be frustrations and disappointments,” Obama said upon his arrival in Washington. “I will make some mistakes.” In other words, don’t expect much....