Don't bank on a repeat performance

In his prime, Martinez contended for the Cy Young nearly every year. He was an exception. Ezra Shaw/Getty Images

As a rule, maintaining greatness is almost as difficult as attaining it. Although there are elite stars in every sport, most athletes find their pre-eminence fleeting. Statheads refer to it as regression toward the mean, while others explain a natural decline from exceptional to average with an array of jinxes and curses. Either way, they describe the same concept.

In baseball, whenever a journeyman hits 25 home runs or comes out of nowhere to win 15 games, there's always a healthy dose of skepticism. In most cases, the skepticism is warranted, as those players who take a huge step forward usually take at least a healthy step back.

With awards week under way, it's worth exploring the question of just how much the best performers tend to regress after their big years. It's easier to think of a pitcher such as Ryan Vogelsong -- who went 13-7, 2.71 ERA for the Giants but boasted a career ERA of 5.86 in the majors before that -- underperforming in 2012. However, it's harder to envision a young star in the prime of his career also disappointing.