Replacement Level Players

One of the core concepts of sabermetric research is that of the "replacement level player". Simply put, the idea is to quantify the level of performance at which a player is expendable. In other words, the level at which a player is easy and cheap to find at that position in the minor leagues. By quantifying replacement level in books such as The Baseball Prospectus it is much easier to see when teams overpay for performance they could get almost for free. For example, in the BP each player listing includes a column for VORP (Value Over Replacement-level Player).

As teams like the A's, Red Sox, Blue Jays and Dodgers begin to integrate measures like VORP into their personnel decisions you'll soon see the situation described in the introduction to the 2004 BP:

"As a result, teams are slowly coming to realize that they have more options than they think when it comes to putting together their minor league roster. Over the next few years, you can reasonably expect to see greater salary stratification among major leaguers, with fewer stars making more money at the very top, a slow deterioration of the 'middle class' of ballplayers, and more and more players earning salaries not far from the league minimum. It's part of the accelerated evolution of the business of baseball taking place in MLB front offices, as a result of better understanding of what's going on between the lines."

I would add that the increasing availability of players from the entire world and not only the western hemisphere will only quicken the process.