One of the obstacles any MLS club faces is the international player limitations. Every club has eight slots when they start out. Some use them wisely, and in the case of Real Salt Lake trading a slot permanently to the Colorado Rapids for Adolfo Gregario (a player so utterly unremarkable that you probably didn’t realize his name was actually Adolfo Gregorio), they use them unwisely.
The Union seem to be using their slots wisely. At current count, they have seven international slots filled our of their eight, as the one that was sent to Houston in 2015 as part of the Sheanon Williams deal came back to Philadelphia on January 1.