More than simply adding the reigning AL Cy Young Award winner, the Phillies added the talent at a very minimal cost. Philadelphia gave up pitchers Carlos Carrasco and Jason Knapp along with infielder Jason Donald and catcher Lou Marson. Sure, these were four of the Phils top-rated prospects, but that might be an indictment of their system rather than praise.
Carrasco is regarded as a good prospect, but hasn't been tearing it up in Triple-A. He has not pitched as poorly as his 5.18 ERA would suggest, but some have questioned whether he has the makeup to be a top starter.
Knapp is regarded as a very good prospect, but he's pretty much just out of high school and currently on the DL with a sore shoulder. Sure, he might turn into the next John Smoltz, but he was years from helping the Phils, who want to win now.
Donald is a decent prospect, but a man without a place in Philly, stuck behind Jimmy Rollins and Chase Utley. He was perfect trade fodder. He, too, has struggled at Triple-A.
Marson is regarded as a decent hitter, less than great defensive catcher. It seems catching prospects rarely live up to expectations, so I'm always for trading them.
Now, factor in that the Phils also got OF Ben Francisco to add some bench depth, and this deal swings even more in the Fightins direction. Francisco is probably not much more than league average, but he's got a little pop. Plus, the Phils can keep Lee at a reasonable price for next season.