If you look over the list of the players the Philadelphia Union either has declined options for or who currently are not on the 2019 first team or Bethlehem Steel FC roster, there is a noticeable quality nearly all of them share.
All but four of the 17 players who are out of contract and haven’t been mentioned by the club as negotiating new contracts (Fabinho with the first team, James Chambers, Matt Mahoney and Drew Skundrich with Steel) entered professional soccer through the MLS SuperDraft. Eight of those 14 former SuperDraft players were drafted by the Philadelphia Union.