The Pittsburgh Pirates have traded infielder Justin Sellers to the Chicago White Sox for a player to be named later or cash considerations. He has been injured most of this season, attempting three rehab comebacks before finally sticking this last time. He had played 16 games this season, mostly in the lower levels.
Deals like this are usually done because a players has an opportunity elsewhere and no spot with the Pirates, so they don't block them from joining another team. That's good business, because minor league free agents will see that a team doesn't bury players in AAA, so they aren't worried about who might be ahead of them on the depth chart.