Austin Jackson started his major league career in Detroit and put up some monster seasons between 2010 to 2012, averaging over 5 bWAR a season for the Tigers. In 2013 and 2014, Jackson missed time with injuries that ultimately lead to a trade to Seattle at the trade deadline in 2014. Jackson hit .272/.312/.387 for the Mariners last season before being traded to the Cubs at the waiver deadline last season.
This move, however, makes one thing clear about where Jackson thinks he is going to play.
That seems to mean that when healthy Adam Eaton will be moving to RF, with Avisail Garcia playing somewhere to be determined.
This move is not yet official and with the 40-man roster at 40, another move will have to be made. We'll keep you updated as the news comes out.
Edit: The White Sox designated Mike Olt for assignment to make room for Jackson.