The Sox were interested in Masset at least a month ago, considering trading Brian Anderson to the Rangers. Masset, a righthander, will turn 25 in May. Baseball America ranked him eighth among Ranger prospects. He had Tommy John surgery as a senior in high school, which could be viewed as a positive (given that his new tendon/ligament doesn't have a lifetime of wear and tear on it). Masset converted to relief this year and was able to dial his fastball into the high 90s. He could be yet another hard thrower in Chicago's explosive bullpen in 2007.
Danks, a southpaw, turns 22 in April. He was the Rangers' best prospect according to BA. He throws three solid pitches and has pitched well in the minors despite being young for his levels. He'll compete for the fifth spot in Chicago's rotation. He's the prize of the deal.
While B-Mac has 150 innings of Major League experience, it'd be tough to argue that he's worth as much as Danks and Masset combined. The 23 year-old was confined to the bullpen in 2006 because the Sox had no openings in the rotation. With groundball rates around 37%, McCarthy doesn't seem particularly suited for Ameriquest. He'll still be a valuable commodity if he can find a way to keep the ball in the yard. You can view my RotoAuthority projection of McCarthy as a Ranger here.
No one thought Kenny Williams would trade McCarthy, but it looks like he got an offer he couldn't refuse. You have to admire that he has a plan and he's sticking to it.