First things first. This deal immediately upgrades the White Sox bullpen, likely sending Sean Tracey to the minors. MacDougal is a skinny fireballing reliever with terrible mechanics and injury issues. Combined with Bobby Jenks, Neal Cotts, and Matt Thornton he gives the Sox 4 high strikeout arms under team control through the '09 season. Being under White Sox control doesn't do much good when your on the DL, however. MacDougal will inherit right-handed set up duties when he isn't rehabbing in AAA Charlotte.
As for the players the White Sox gave up. Tyler Lumsden was drafted as a sandwich pick in the '04 draft. He struggled in his first season of professional baseball largely because he was injured. He sat out all of last season recovering from off-season surgery, and has returned to top form this season. Lumsden has a heavy fastball that sits around 92-93 and can touch 95 or higher, a rare trait for a left-handed pitcher. He also features a good slider and has the best GB/FB ratio of any Sox starting pitching prospect.
Daniel Cortes was an 8th round draft pick last season. He's got a large frame and a live arm. He struggled early this season as the youngest player on a bad Kannapolis club, but has rebounded to be one of the top pitchers in the Sally League the last 2+ months. He's years away from sniffing the major leagues, but he might have the second best arm, behind Lumsden, in the Sox system.
The Sox are a better team right now, thank to this deal, but you have got to get a better return on trades involving your top minor league arms. The White Sox bullpen was largely put together thanks to a number of shrewd moves by Kenny Williams; Bobby Jenks off of waivers, David Riske for a non-roster invitee, Matt Thornton for a DFA candidate.
Given the volatility of bullpen arms, MacDougal's inability to stay on the field, and the relatively cheap price Williams has paid for bullpen help in the past, this deal looks like a huge overpay by the Sox.
Sean Tracey was optioned to Charlotte to make room for MacDougal.