Players in any sport who are having great seasons

Players in any sport who are having great seasons, turning in performances that are much better than anyone might have anticipated, often are pictured on the cover of Sports Illustrated. Frequently, their performances then falter somewhat, leading some athletes to believe in a “Sports Illustrated jinx.” Similarly, it is common for phenomenal rookies to have less stellar second seasons the so-called “sophomore slump.”

While fans, athletes, and analysts have proposed many theories about what leads to such declines, a statistician might offer a simpler (statistical) explanation. Explain.