Quick scouting reports on the first four after the jump.
I'll start with the mild surprise and the guy with whom people are least familiar. Infante wasn't in my list of candidates from this weekend but, after watching the bullpen struggle some more and seeing the lack of Infante on the Arizona Fall League roster announced today (not to mention the cryptic tweets out of Birmingham), I'm not all that surprised. The 23 year old Venezuelan converted to relief this season and made short work of High A before moving on to AA midseason. The righty has a nice fastball that sat in the low to mid 90s as a starter and reportedly now gets into the upper 90s out of the bullpen. His second pitch is a plus curve. He presumably has dropped his erratic changeup now that he's relieving. With the Dash and Barons he struck out 10.5 per 9 but also walked 4 per 9. The White Sox are desperate for bullpen help and Infante, long a favorite of the organization, can bring the heat Kenny Williams loves out of his relievers.
De Aza has done all that you could ask of him this season (.302/.366/.440), other than stay healthy. Except for that rather large and frequent failing, the outfielder is a legit major league player. While he cannot hit lefties, he does hit righties well. He can play all three outfield spots, makes contact, does a decent job of getting on base, has a little pop and can steal bases. Essentially, he's your prototypical 4th outfielder.
Flowers garnering the ceremonial third catcher spot suggests that the White Sox still have some faith in the 24 year old. Flowers' contact issues have been well-documented, resulting in a .220/.334/.434 line for Charlotte. Of course, that line also shows that he still is getting on base and still hitting for power when he does manage to make contact, so there is still some hope for him.
Everyone is very familiar with Viciedo. He didn't take well to his demotion, putting up a .224/.234/.395 since going back to Charlotte. He also continued to butcher it up in the field. What he can provide is a power bat off the bench, particularly against lefties.