The White Sox minor league system is improving. That statement can be viewed in one of two ways: The system is so bad that it hit rock bottom and has nowhere to go but up; or the Sox have begun to add enough potential to the point where the system has shown some real improvement.
I'm more in the middle of this. The Sox system really did have nowhere to go but up before the team acquired Nestor Molina, but at the same time, the Sox do have a decent stable of power arms in the system.
That being said, a lot of those power arms project as relievers right now, most notably Jake Petricka and Simon Castro. Molina is the only pitcher in the Sox system who I'm confident will start in the majors (barring injury, of course). While having bullpen arms is nice, having a stable of starters is far more important. The Sox will need quite a few pitchers to develop third pitches before they can have that all-important starting pitching depth.
The Sox are also incredibly thin in terms of position players. Trayce Thompson is an intriguing prospect, and Tyler Saladino could be a decent major leaguer, but beyond those guys there isn't anyone I'm too excited about.
But with Marco Paddy and the new CBA, the Sox are in a position to get out of the farm system cellar at some point in the near future. It may not be next year, but as the playing field is leveled to the White Sox plane, the Sox farm system won't be as barren as it is now.
Check out CTL's discussion on this topic -- I like Phil Rogers' point that the Sox have excellent scouts and minor league coaches, both of which will be key as teams are capped from spending tons of money on prospects.