Brett Myers, probably best known among fans for his arrest for allegedly assaulting his wife in 2006 (charges were dismissed after his wife said she did not want Myers prosecuted), had value as a starter in 2010 and 2011, primarily for his ability to soak up innings, but was just a replacement-level reliever thus far in 2012, giving up 17 runs in 30.2 innings with just 20 punchouts. That last figure reflects the fact that his repertoire is deep -- five separate pitches -- but offers nothing plus, with his best attribute his ability to slightly cut his fastball without giving up velocity, helping generate some ground balls. He rarely walks guys and has plenty of options for changing speeds. The net gain to the White Sox is marginal, less than a win, although Don Cooper has worked miracles before with other pitchers who have underperformed elsewhere.
In exchange for Myers, the Astros get two depth starters who barely qualify as prospects, plus a player to be named later. Right-hander Matt Heidenreich is up to 91 mph with an above-average changeup, above-average command and control, and a good feel for pitching, but in the best-case scenario, he is probably a good fifth starter, and he more likely tops out as an up-and-down guy. Left-hander Blair Walters will show an average fastball up to 92 mph and changeup, but neither of his breaking balls is average, with the curve and slider running together and often finishing out of the zone. He also doesn't have the platoon splits to point to a future as a specialist.
Neither guy is likely to be a top-20 prospect in this system by year's end. Houston also saves $1 million and avoids the threat of Myers' $10 million vesting option for 2013 (triggered if he finishes 16 games between now and the end of the season), more valuable than either of the players returned.