The change in the collective bargaining agreement forcing smaller market teams to spend their money on baseball rather than lining the owners pockets? Just a guess.
Perhaps more concrete is the way of evaluating value in the first place. If value is seen (as I've written about in past posts, and as mentioned in baseball between the numbers) as different depending on the team that is spending the money, then a lot of what has happened ths year makes sense. the teams that have spent the most on players are those who are closest to being "over the hump" in terms of playoff contention. the goal is to make the playoffs, winning the WS is an on the field goal, but I don't think it is a realistic thing for any team to aim at at this point in the season.
So, the teams that I have seen spending the most (Dodgers, Astros, Cubs, Red Sox) are all likely planning on spending to the point where they have added enough wins to get into the 93+ wins category (with luck, health, etc., of course). The value for a player like Soriano added onto a lineup with Lee and Ramirez is considerably more than it is for a player like Soriano added to the Royals (he might bring them from 72 wins to 76, no increased profit). If Boras were smart enough to look at the needs of the upper-middle class teams--in terms of current mlb talent, last year's record and ability to spend--(which he is) and if he believed that these large market teams acted like most large market teams a few players away from the playoffs would be expected to behave (which they did), then its not difficult to predict that there would be an up-swing of $$ paid to even marginal FA's.
Despite baseball's reputation for having uneven payrolls and supposedly talent, there are a lot of teams between the .500 and .560 win% who are capable of spending money to contend. Texas, seattle, San Diego, St. Louis, Houston, Detroit, both Chicagos, Boston, both New Yorks, etc., the list of non contending teams is much smaller than the list of contending teams. In an environment like that, with a basic understanding of supply and demand it isn't impossible to predict that JD Drew could get more than 11 million a year. ESPECIALLY after a largely healthy season.
This guy was a former #2 and #5 overall pick in 97 and 98. His talent is not the question here. If he's healthy he's worth more than 11m in today's game.