Popping the Question: who -- or what -- is an MVP candidate?

As the season enters its final month, predicting baseball's playoff teams is a tricky exercise. Following the pennant races requires daily scoreboard watching and magic number recalculation. This is especially true in the National League, where every club except Washington, Chicago and Pittsburgh is within five games of the Wild Card spot.

Amid constant realignment of standings, flurries of last-second waiver deals and potentially devastating injuries, there is still so much baseball left that the process of forecasting October matchups may seem a trifling matter, although knowing this doesn't stop us from staying up late at night, wondering if Josh Rabe will get postseason at bats against lefties, and how Jeff Weaver might figure into the Cards' playoff rotation, for example.

No less daunting a challenge, and thus all the more ripe for debate, is the task of identifying the player in each league who is deserving of the MVP award.

Ah, the Most Valuable Player. Just typing the words brings frustration. The award's winner must perform at a level of superlative excellence, yet the methods for identifying excellent performance are superlatively undefined. Must he come from a playoff team? Has he driven in lots of runs? Produced without lineup protection? Does he dazzle in the field? Can he raise his game against rival teams? How clutch is he? To get to the heart of the MVP debate, we must decide what qualities are important in a candidate, and then we can attempt to quantify these qualifications.

Of course, this is easier said than done.

Consider the phrase in whole: Most Valuable Player. Not a single word of the three clarifies our expectation of who should be among those discussed as candidates. After all, what constitutes a "player?" Does this designation apply only to fielders who "play," or do "players" designated as hitters fit the bill? What about pitchers? Are they not "players?" Before we can differentiate among different types of "value," gauge their varying capacities to be measured, and extrapolate a ranking of these metrics, arguments for who is eligible as a "player" stand to complicate the discussion.

Just as the Wild Card has impacted the dynamics of September (and October) baseball, discourse on the MVP award has shifted accordingly. Over the coming days and weeks, I will study the threads of logic and preference that have produced the MVP finalists of the last dozen seasons. By focusing on the top end of each ballot, I hope to determine what qualities are favored in the selection of certain candidates over others as most valuable. My findings will be based on data available at Baseball-Reference.com and Retrosheet.org, and other sources, as noted.

(Note: While it may be difficult, I will try to avoid treating the voting bloc of the Baseball Writers' Association of America (BBWAA) as a monolithic entity, and parse the behavior of its members into distinct categories as best I can -- with the data available. Any reader who is able to provide me with links or information about confirmed, actual complete MVP ballots as submitted by BBWAA members would be extremely helpful, as my own research efforts to collect such data have produced few successes.)