The Capitals pushed to sign the forward before his junior season at Boston College.
After playing a season in Zurich with Auston Matthews, Jonas Siegenthaler suited up for Hershey, but ended his season early.
Two Caps development camp players have signed contracts within the organization.
Hobbs is at Washington's development camp this week.
"I’m a big believer in earning everything, and at the end of the day, he seemed to fit that bill," goaltending coach Mitch Korn said of Carlson.
Travis Boyd is participating in his sixth development camp, despite playing his last game of the AHL season on June 11.
Garrett Pilon said he typically avoids fighting, unlike his father, who'd been in scores of them as an NHL player.
Jay Williams, a McLean native, goes from cheering for the team to trying to make the team.
Bowey is one of Washington's top prospects at development camp this week.
Attendees include 2016 first-round pick Lucas Johansen and 2015 first-rounder Ilya Samsonov.