Trading for a player like Roy Halladay is not a value-based maneuver; it is a statement.
The Philadelphia Phillies had lost the 2009 World Series to the New York Yankees. When they managed to package several top prospects and land Halladay from the Toronto Blue Jays that winter, they made it clear that they would not accept less than elite status in the National League for the long-term.
Halladay isn't the only example of this phenomenon, of course. High-profile trades happen every year, and some of them can alter the direction of the franchises involved. They're exciting for fans of any team, because they represent a bold wager:
"Here's our superstar," says Team A. "We feel we're better off with your top three prospects."
"Maybe you will be," replies Team B. "But we're going to win titles with your erstwhile stud at the front of our rotation, or in the middle of our lineup."
That's exhilarating. It's fun to watch teams challenge each other. It's also fun, of course, when it blows up in one team's face.
Here are the 50 biggest trades in MLB history, based on the reaction to the deal at the time. No Lou Brock or Jeff Bagwell here, as those were under-the-radar moves that surprised everyone when they turned out to be mega-deals.