Without capgeek, I don't know how to check, but I'm guessing that's rights/waiverstatus-related.
By my calculations, Dumoulin shouldn't need waivers until next season which makes his lack of NHL game time even more confusing.
Dumoulin signed his ELC in April 2012 at age 20. Based on age at signing, within three years of signing or less than 160 NHL GP, he is waiver exempt
according to the CBA. Dumoulin has only played 14 NHL games, and three years doesn't expire until the end of the season.
Even if his signing age was 21 (not 20), he would be waiver exempt for three years and 80 NHL games.
For Despres, accoringing to the CBA, unrestricted free agents are:
Any Player who either has seven (7) Accrued Seasons or is 27 years of age - Group 3 UFA
Any Player who has completed ten (10) or more professional seasons (minor league or NHL seasons, but excluding any season in Major Juniors) - Group 5
Any Player who is age 25 or older who has completed three (3) or more professional seasons and: (i) in the case of a Player other than a goaltender, has played less than 80 NHL Games, or (ii) in the case of a goaltender, has played less than 28 NHL Games (for the purpose of this definition, a goaltender must have played a minimum of thirty (30) minutes in an NHL Game to register a game played). - Group 6
Draft-related Free Agents
Undrafted free agents
Despres doesn't meet any of the requirements to become a UFA.
EDIT:
Source? I'm assuming his free agency status is something the team would have told DK
The CBA.